Month: January 2022

Right now it is approaching the end of January and this week’s blog is slightly longer than usual. Last month we had the shortest day of the year in terms of daylight, which means quite a few people should begin to feel happier now that our sun rises at an earlier time each day! Of course, we become used to that and then the clocks in the UK go forward an hour. Moon phases reveal the passage of time in the night sky and on some nights when we look up at the moon it is full and bright, whilst sometimes it is just a sliver of silvery light. These changes in appearance are the phases of the moon and as the moon orbits Earth, it cycles through eight distinct phases. The four primary phases of the moon occur about one week apart, with the full moon its most dazzling stage. For example we had a New Moon on January 2, a First Quarter on January 9, a Full Moon on January 17 and a Last Quarter on January 25. Then we are back to a New Moon on February 1, which will signal the beginning of the Lunar New Year. This is also called Chinese New Year and will signal the ‘Year Of The Water Tiger’. A New Moon is when our satellite is between the Earth and the Sun, so it’s not visible to us. Technology has progressed so much now and more folk take such excellent photos of the moon and other stellar objects. In addition, we can share these with family, friends, almost anyone we wish to via the Internet technology so many of us can access. But not everyone has either the access to or even the wish to use things like Facebook, Messenger, WhatsApp, Zoom and so many others too numerous to mention. In my early days of taking photographs I used a very simple and straightforward camera, a Kodak Instamatic. Once used, I would take the film in to a local camera shop where the film would be developed and a few days later I would return to that shop to collect my pictures. Sometimes I would be pleased with the results and other times not, but I could at times get some advice a friendly shop assistant who was a photographer. I really did learn much in those early days and I am grateful even now for the help I received. I have written in a previous blogs about the different cameras I have had, from the basic ‘point and click’ up to the modern Single Lens Reflex (SLR) ones where a prism and mirror system is used to view an image exactly before it is stored electronically on a memory card. Images can now be modified, linked, such things as their brightness and contrast adjusted, all at the click of a button. Videos are made quickly and easily using simple smart phones, even if they only last a few seconds. I have no doubt that in time, more ideas will provide what to many will be seen as bigger as well as better. But we should surely not lose sight of the past, the basics, the simple ideas. There are many who will come up with new ideas, but they cannot be expected to create them at will. Likewise, those with new ideas give rise to further developments. As an example, I have previously mentioned in an earlier blog post about Guy Fawkes and the Gunpowder Plot.

Gunpowder is the first explosive to have been developed. Popularly listed as one of the ‘Four Great Inventions’ of China, the others being the compass, paper making and printing. Gunpowder was invented during the late Tang Dynasty in the 9th century, whilst the earliest recorded chemical formula for gunpowder dates to the Song Dynasty of the 11th century. The knowledge of gunpowder spread rapidly throughout Asia, the Middle East and Europe, possibly as a result of Mongol conquests during the 13th century, with written formulas for it appearing in the Middle East between 1240 and 1280 in a treatise by Hasan-al-Rammah and in Europe by 1267 in the ‘Opus Majus’ by Roger Bacon. It was employed in warfare to some effect from at least the 10th century in weapons such as fire arrows, bombs and the fire lance before the appearance of the gun in the 13th century. In fact whilst the fire lance was eventually supplanted by the gun, some other gunpowder weapons such as rockets and fire arrows continued to see use in China, Korea, India, and eventually Europe. Gunpowder has also been used for non-military purposes such as fireworks for entertainment, as well as in explosives for mining and tunnelling. The evolution of guns then led to the development of large artillery pieces, popularly known as bombards, during the 15th century and pioneered by states such as the Duchy of Burgundy. Firearms came to dominate early modern warfare in Europe by the 17th century and the gradual improvement of cannons firing heavier rounds for a greater impact against fortifications led to the invention of the star fort and the bastion in the Western world, where traditional city walls and castles were no longer suitable for defence. The use of gunpowder technology also spread throughout the Islamic world as well as to India, Korea and Japan. The use of gunpowder in warfare during the course of the 19th century diminished due to the invention of smokeless powder and as a result, gunpowder is often referred to nowadays as ‘black powder’ to distinguish it from the propellant used in contemporary firearms.

The earliest reference to gunpowder seems to have appeared in 142AD during the Eastern Han dynasty. It is said that an alchemist by the name of Wei Boyang was known as the ‘father of alchemy’ and wrote about a substance with gunpowder-like properties which described a mixture of three powders that would “fly and dance” violently in the ‘Book of the Kinship of Three’, a Taoist text on the subject of alchemy. However, Wei Boyang is considered to be a semi-legendary figure meant to represent a ‘collective unity’, and was probably written about in stages from the Han dynasty to 450AD. Although not specifically named, the powders were almost certainly the ingredients of gunpowder and no other explosive known to scientists is composed of such powders. Whilst it was almost certainly not their intention to create a weapon of war, Taoist alchemists continued to play a major role in the development of gunpowder due to their experiments with sulphur and saltpetre, although one historian has considered that despite the early association of gunpowder with Taoism, this may be a quirk of historiography and a result of the better preservation of texts associated with Taoism, rather than being a subject limited to only Taoists. Their quest for the elixir of life certainly attracted many powerful patrons, one of whom was Emperor Wu of Han. The next reference to gunpowder occurred in the year 300AD during the Jin dynasty and a Taoist philosopher wrote down all of the ingredients of gunpowder in his surviving works, collectively known as the ‘Baopuzi’. In 492AD, some Taoist alchemists noted that saltpetre, one of the most important ingredients in gunpowder, burns with a purple flame allowing for practical efforts at purifying the substance and during the Tang dynasty, alchemists used saltpetre in processing the four yellow drugs, namely sulphur, realgar, orpiment and arsenic trisulphide. Taoist text warned against an assortment of dangerous formulas, one of which corresponds with gunpowder, in fact alchemists called this discovery ‘fire medicine’ and the term has continued to refer to gunpowder in China into the present day, a reminder of its heritage as a side result in the search for longevity increasing drugs. A book published in 1185AD called ‘Gui Dong’, The Control of Spirits, also contains a story about a Tang dynasty alchemist whose furnace exploded, but it is not known if this was caused by gunpowder. The earliest surviving chemical formula of gunpowder dates to 1044AD in the form of the military manual, known in English as the ‘Complete Essentials for the Military Classics’, which contains a collection of facts on Chinese weaponry. However this edition has since been lost and the only currently extant copy is dated to 1510AD during the Ming dynasty. Gunpowder technology also spread to naval warfare and in 1129AD it was decreed that all warships were to be fitted with trebuchets for hurling gunpowder bombs.

By definition, a gun uses the explosive force of gunpowder to propel a projectile from a tube so cannons, muskets, and pistols are therefore typical examples. In 1259AD a type of fire-emitting lance was made from a large bamboo tube, with a pellet wad stuffed inside it. Once the fire goes off, it completely spews the rear pellet wad forward, and it has been said that “the sound is like a bomb that can be heard for five hundred or more paces”. The pellet wad mentioned is possibly the first true bullet in recorded history. Fire lances transformed from the bamboo, wood or paper-barrelled firearm to the metal-barrelled firearm in order to better withstand the explosive pressure of gunpowder. From there it branched off into several different gunpowder weapons known as ‘eruptors’ in the late 12th and early 13th centuries. The oldest extant gun whose dating is unequivocal is the Xanadu Gun because it contains an inscription describing its date of manufacture corresponding to 1298AD. It is so called because it was discovered in the ruins of Xanadu, the Mongol summer palace in Inner Mongolia. The design of the gun includes axial holes in its rear which some speculate could have been used in a mounting mechanism. Another specimen, the Wuwei Bronze Cannon, was discovered in 1980 and may possibly be the oldest as well as largest cannon of the 13th century though a similar weapon was discovered in 1997, but much smaller in size. So it seems likely that the gun was born sometime during the 13th century. Gunpowder may have been used during the Mongol invasions of Europe, as shortly after the Mongol invasions of Japan which was from 1274AD to 1281AD, the Japanese produced a scroll painting depicting a bomb and is speculated to have been the Chinese thunder crash bomb. Japanese descriptions of the invasions also talk of iron and bamboo ‘pao’, causing light and fire and emitting 2 to 3,000 iron bullets.

A common theory of how gunpowder came to Europe is that it made its way along the Silk Road, through the Middle East. Another is that it was brought to Europe during the Mongol invasion in the first half of the 13th century. Some sources claim that Chinese firearms and gunpowder weapons may have been deployed by Mongols against European forces at the Battle of Mohi in 1241AD, it may also have been due to subsequent diplomatic and military contacts. Some authors have speculated that William of Rubruck, who served as an ambassador to the Mongols from 1253AD to 1255AD, was a possible intermediary in the transmission of gunpowder. The 1320s seem to have been the takeoff point for guns in Europe according to most modern military historians. Scholars suggest that the lack of gunpowder weapons in a well-traveled Venetian’s catalogue for a new crusade in 1321AD implies that guns were unknown in Europe up until this point but guns spread rapidly across Europe There was a French raiding party that sacked and burned Southampton in 1338AD who brought with them a ribaudequin, a late medieval volley gun with many small-calibre iron barrels set up in parallel on a platform. It was in use during the 14th and 15th centuries and when the gun was fired in a volley, it created a shower of iron shot. But the French brought only 3 pounds of gunpowder. Around the late 14th century European and Ottoman guns began to deviate in purpose and design from guns in China, changing from small anti-personnel and incendiary devices to the larger artillery pieces most people imagine today when using the word “cannon”, If the 1320s can be considered the arrival of the gun on the European scene, then the end of the 14th century may very well be the departure point from the trajectory of gun development in China. In the last quarter of the 14th century, European guns grew larger and began to blast down fortifications.

In India, gunpowder technology is believed to have arrived by the mid-14th century, but could have been introduced much earlier by the Mongols, who had conquered both China and some borderlands of India, perhaps as early as the mid-13th century. The unification of a large single Mongol Empire resulted in the free transmission of Chinese technology into Mongol conquered parts of India. Regardless, it is believed that the Mongols used Chinese gunpowder weapons during their invasions of India. The first gunpowder device, as opposed to naphtha-based pyrotechnics, introduced to India from China in the second half of the 13th century, was a rocket called the ‘hawai’. The rocket was used as an instrument of war from the second half of the 14th century onward, and the Delhi sultanate as well as Bahmani kingdom made good use of them.

As a response to gunpowder artillery, European fortifications began displaying architectural principles such as lower and thicker walls in the mid-1400s. Cannon towers were built with artillery rooms where cannons could discharge fire from slits in the walls. However this proved problematic as the slow rate of fire, reverberating concussions, and noxious fumes produced greatly hindered defenders. Gun towers also limited the size and number of cannon placements because the rooms could only be built so big. The star fort, also known as the bastion fort, was a style of fortification that became popular in Europe during the 16th century. These were developed in Italy and became widespread in Europe. The main distinguishing features of the star fort were its angle bastions, each placed to support their neighbour with lethal crossfire, covering all angles, making them extremely difficult to engage with and attack. By the 1530s the bastion fort had become the dominant defensive structure in Italy. Outside Europe, the star fort became an ‘engine of European expansion’ and acted as a force multiplier so that small European garrisons could hold out against numerically superior forces. Wherever star forts were erected, the natives experienced great difficulty in uprooting European invaders. In China, bastion forts were advocated for the construction so that their cannons could better support each other. Gun development and design in Europe reached its most classic form in the 1480s, as they were longer, lighter, more efficient, and more accurate compared to predecessors only three decades prior and the design persisted. The two primary theories for the appearance of the classic gun involve the development of gunpowder corning and a new method for casting guns. The ‘corning’ hypothesis stipulates that the longer barrels came about as a reaction to the development of corned gunpowder. Not only did corned powder keep better, because of its reduced surface area, but gunners also found that it was more powerful and easier to load into guns. Prior to corning, gunpowder would also frequently de-mix into its constitutive components and was therefore unreliable. The faster gunpowder reaction was suitable for smaller guns, since large ones had a tendency to crack, and the more controlled reaction allowed large guns to have longer, thinner walls. In India, guns made of bronze have been recovered from Calicut (1504AD) and Diu (1533AD). By the 17th century a diverse variety of firearms were being manufactured in India, large guns in particular. Gujarat supplied saltpetre in Europe for use in gunpowder warfare during the 17th century and the Dutch, French, Portuguese, and English used Chāpra as a centre of saltpetre refining. Aside from warfare, gunpowder was used for hydraulic engineering in China by 1541. Gunpowder blasting followed by dredging of the detritus was a technique which Chen Mu employed to improve the Grand Canal at the waterway where it crossed the Yellow River. In Europe, it was utilised in the construction of the ‘Canal du Midi’ in Southern France and which was completed in 1681 and linked the Mediterranean sea with the Atlantic with 240km of canal and 100 locks. But before gunpowder was applied to civil engineering, there were two ways to break up large rocks, by hard labour or by heating with large fires followed by rapid quenching. The earliest record for the use of gunpowder in mines comes from Hungary in 1627AD. It was introduced to Britain in 1638AD by German miners, after which time records are numerous but until the invention of the safety fuse in 1831, the practice was extremely dangerous. Another reason for danger were the dense fumes given off and the risk of igniting flammable gas when used in coal mines. Gunpowder was also extensively used in railway construction. At first railways followed the contours of the land, or crossed low ground by means of bridges and viaducts, but later railways made extensive use of cuttings and tunnels. One 2400-ft stretch of the 5.4 mile Box Tunnel on the Great Western Railway line between London and Bristol consumed a ton of gunpowder per week for over two years. Then there is the Fréjus Rail Tunnel, also called Mont Cenis Tunnel, which is a rail tunnel some 8.5 miles (13.7 kilometres) length in the European Alps, carrying the Turin-Modane railway through Mont Cenis to an end-on connection with the Cult-Modane railway and linking Bardonecchia in Italy to Modane in France. The tunnel was completed in 13 years starting in 1857AD but, even with black powder, progress was only 25 centimetres a day until the invention of pneumatic drills, which speeded up the work. However, the latter half of the 19th century saw the invention of nitroglycerin along with nitrocellulose and smokeless powders which soon replaced traditional gunpowder in most civil and military applications. Believe it or not, there is so much more to tell on this subject and as you can see, we have learned and developed so much over the centuries. I am sure we will continue to do so. As always, I hope that it will be for the good, for the benefit of all.

This week…
A great deal has been written about marriage. I once saw the following quote: “Marriage is an institution – but not everyone wants to live in an institution”. Another is “Marriage can be like a deck of cards. At the beginning, all you need are two hearts and a diamond, but in the end you wish you had a club and a spade”…

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As we go through life, change is all around us, day by day. I have written about our universe, our sun and the planets, including this Earth which has changed over millions of years. Though it is only a relatively short space of time that as humans we have been recording these developments, with the technology we have developed and the skills we have learned we can look back and see what has occurred. But these changes are continuing and we are having a marked effect on them. This Earth still spins, seasons change, life ends and new life begins. In many species it develops, as it adapts to the changes that are made. But many species are no longer with us. I was watching an item on YouTube about changes being made to the Catthorpe Interchange on the M1 motorway and how newts had been discovered there. As a result, changes were made to the area where they were in order to preserve it whilst they grew and eventually moved. A newt is a form of salamander, which are a group of amphibians typically characterised by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. Their diversity is highest in the Northern Hemisphere. They rarely have more than four toes on their front legs and five on their rear legs, but some species have fewer digits and others lack hind limbs. Their permeable skin usually makes them reliant on habitats in or near water or other cool, damp places. Some species are aquatic throughout their lives, some take to the water intermittently, and others are entirely terrestrial as adults. They are capable of regenerating lost limbs as well as other damaged parts of their bodies and researchers hope to reverse engineer this remarkable regenerative processes for potential human medical applications, such as brain and spinal cord injury treatment or preventing harmful scarring during heart surgery recovery. The skin of some species contains the powerful poison tetrodotoxin and as a result these salamanders tend to be slow-moving and have a bright warning colouration in order to advertise their toxicity. Salamanders typically lay eggs in water and have aquatic larvae, but great variation occurs in their lifecycles. Newts metamorphose through three distinct developmental life stages: aquatic larva, terrestrial juvenile (eft), and adult. Adult newts have lizard-like bodies and return to the water every year to breed, otherwise living in humid, cover-rich land habitats. They are therefore semiaquatic, alternating between aquatic and terrestrial habitats. Not all aquatic salamanders are considered newts, however. More than 100 known species of newts are found in North America, Europe, North Africa and Asia. Newts are threatened by habitat loss, fragmentation and pollution. Several species are endangered, and at least one species, the Yunnan lake newt, has recently become extinct as it was only found in the shallow lake waters and adjacent freshwater habitats near the Kunming Lake in Yunnan, China. The Old English name of the animal was ‘efte’ or ‘efeta’ (of unknown origin), resulting in the Middle English ‘eft. This word was transformed irregularly into ‘euft’, ‘evete’ or ‘ewt(e)’. The initial “n” was added from the indefinite article “an” by the early 15th century. The form “newt” appears to have arisen as a dialectal variant of ‘eft’ in Staffordshire, but entered Standard English by the Early Modern period where it was used by Shakespeare in ‘Macbeth’. The regular form ‘eft’, now only used for newly metamorphosed specimens, survived alongside ‘newt’, especially in composition, the larva being called “water-eft” and the mature form “land-eft” well into the 18th century, but the simplex ‘eft’ as equivalent to “water-eft” has been in use since at least the 17th century. Dialectal English and Scots also has the word ‘ask’’, also ‘awsk’ and ‘esk’ in Scots used for both newts and wall lizards from Old English, from photo-Germanic , literally ‘lizard-badger’ or ‘distaff-like lizard’. Latin had the name ‘stellio’ for a type of spotted newt, Ancient Greek had the name κορδύλος, presumably for the water newt (immature newt, or eft). German has ‘Molch’, from Middle High German. Newts are also known as ‘Tritones’, named for the mythological Triton in historical literature, and ‘triton’ remains in use as common name in some Romance languages, in Greek, in Romanian, Russian, and Bulgarian.

Newts are found in North America, Europe, North Africa and Asia. The Pacific newts and the Eastern newts are amongst the seven representative species in North America, whilst most diversity is found in the Old World. In Europe and the Middle East, eight genera with roughly 30 species are found, with the ribbed newts extending to northernmost Africa. Eastern Asia, from Eastern India over Indochina to Japan, is home to five genera with more than 40 species. As I have mentioned, newts are semiaquatic, spending part of the year in the water for reproduction and the rest of the year on land. Whilst most species prefer areas of stagnant water such as ponds, ditches or flooded meadows for reproduction, some species such as the Danube Crested newt can also occur in slow-flowing rivers. In fact the European brook newts and European mountain newts have even adapted to life in cold, oxygen-rich mountain streams. During their terrestrial phase, newts live in humid habitats with abundant cover such as logs, rocks, or earth holes. Newts share many of the characteristics of their salamander kin, including semipermeable glandular skin, four equal-sized limbs, and a distinct tail. However, the skin of the newt is not as smooth as that of other salamanders. The cells at the site of an injury have the ability to un-differentiate, reproduce rapidly and differentiate again to create a new limb or organ. One hypothesis is that the un-differentiated cells are related to tumour cells, since chemicals that produce tumours in other animals will produce additional limbs in newts. In terms of development, the main breeding season for newts in the Northern Hemisphere is in June and July. After courtship rituals of varying complexity, which take place in ponds or slow-moving streams, the male newt transfers a spermatophore, which is taken up by the female. Fertilised eggs are laid singly and are usually attached to aquatic plants. This distinguishes them from the free-floating eggs of frogs or toads, which are laid in clumps or in strings. Plant leaves are usually folded over and attached to the eggs to protect them. The larvae, which resemble fish fry but are distinguished by their feathery external gills, hatch out in about three weeks. After hatching, they eat algae, small invertebrates, or other amphibian larvae. During the subsequent few months, the larvae undergo metamorphosis, during which they develop legs, whilst the gills are absorbed and replaced by air-breathing lungs. At this time some species, such as the North American newts, also become more brightly coloured. Once fully metamorphosed, they leave the water and live a terrestrial life, when they are known as ‘efts’. Only when the eft reaches adulthood will the North American species return to live in water, rarely venturing back onto the land. Conversely, most European species live their adult lives on land and only visit water to breed.

Many newts produce toxins in their skin secretions as a defence mechanism against predators. ‘Taricha’ newts of western North America are particularly toxic and the rough-skinned newt of the Pacific Northwest actually produces more than enough tetrodotoxin to kill an adult human. In fact some native Americans of the Pacific Northwest used the toxin to poison their enemies! However, the toxins are only dangerous if ingested or otherwise enter the body, for example through a wound. Newts can safely live in the same ponds or streams as frogs and other amphibians and most newts can be safely handled, provided the toxins they produce are not ingested or allowed to come in contact with mucous membranes or breaks in the skin. I have also learned that newts, as with salamanders in general and other amphibians, serve as bioindicators and this is because their thin, sensitive skin and evidence of their presence (or absence) can serve as an indicator of the health of the environment. Most species are highly sensitive to subtle changes in the pH level of the streams and lakes where they live. Because their skin is permeable to water, they absorb oxygen and other substances they need through their skin. This is why scientists carefully study the stability of the amphibian population when studying the water quality of a particular body of water.

But of course that is just one example of changes on this Earth and this to me is why it is so very important to be aware of change. I know that change occurs all the time, change is healthy in so many ways. But so often people make changes in a very selfish way, with no thought as to what impact it may have, whether it be on the people around us, on the plants and animals, even to Earth itself. It has been said that many years ago an animal was left on an island, albeit by accident perhaps, but but that single animal then preyed on a species local to the island and wiped the species out completely. But the animal could not have been brought to that island without human intervention. We have very strict controls on our borders, as most if not all countries do, and yet there are those who flout the rules, not thinking that the rules should apply to them. A while ago I learned of Birds Nest soup, called the ‘Caviar of the East’ but rather than being made from twigs and bits of moss, it is made from the hardened saliva from Swiftlets and dissolved in a broth. It is a Chinese delicacy, is high in minerals like calcium, magnesium and potassium and is extremely rare and valuable. However, because it is an animal product, it is subject to strict import restrictions, particularly with regard to H5N1 avian flu, which could cause an epidemic if brought in to another country. But some people attempt to bring this item over from such places as China, hiding it in their luggage, even though they are warned not to. It is potentially dangerous to bring such items into another country because of the harm it can do. Nowadays we travel around the world far more easily, we can get on an aircraft and be on the other side of the world in a matter of hours, a trip that would at one time have taken us weeks. I was fortunate enough to have a superb holiday a few years ago which took me around the world to Australia and New Zealand, then up to the United States of America, with a number of superb stopping-off places in between. A few years before I had flown to the U.S.A. and wherever I went, the same strict border controls were in place. In fact, prior to my long cruise I had to have a few vaccinations, with proof that I had done so and whilst boarding at Southampton a few passengers were not permitted to travel because they had not been vaccinated. As a result, they had to make their own way to our next port of call, which was Tenerife, after they had been. Right now we are still in the midst of a pandemic, though there are those who have differing views on it, both in terms of its effect and its treatment. Only time will tell. As expected, it is having a marked effect on us, on our daily lives, the health and welfare of everyone. It is changing how we live, how we interact with family and friends and how we cope. Some I know are coping better than others. There is no doubt that we all have a collective responsibility to manage in these troubled times, to believe the people who are skilled in medicine and not be swayed by the people who only think selfishly of themselves. As I wrote in a blog post last year, some folk want the newest, the latest things, they treasure possessions whilst others consider money itself to be important. It does not matter what country they are from. There are those who say that money is the root of all evil, but they are in fact misquoting from the Bible, as the correct version is “For the love of money is the root of all of evil: which while some coveted after, they have erred from the faith, and pierced themselves through with many sorrows”. ~ 1 Timothy 6:10. So it is not the love of money, it is what is done with it that matters. We read so often how people seek both peace and contentment and it is often those who lead a simpler life without many possessions who are, as they have enough food and clothing for themselves and they do what they can to help others. They give thanks every day for all things in their lives, the good and the not so good. Such folk are content. But if those who have money would share it with those who have less, even if it was to simply increase a worker’s basic wage, it would make such a tremendous difference. That is a change which many would gladly accept.

This week I was reminded…
Of a large shop in Peterborough which, many years ago, clearly had a central cash office. As I recall, to pay for goods your money was handed over to an assistant who put it, along with an invoice, into a plastic container. This was placed into a pneumatic pipe system which went between departments, the container whizzed along, your cash was taken and a receipt returned in the same way. I believe that in some areas, even telephone exchanges used them. It is nothing like the electronic systems we use today!

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Last week I wrote about how the Sun, along with the planets, were thought to have been formed. This time I will say a bit more about the colonisation of the land, a bit about extinctions and then talk about our human evolution and its history.

I said last week that the Huronian ice age might have been caused by the increased oxygen concentration in the atmosphere, which caused the decrease of methane (CH4) in the atmosphere. Methane is a strong greenhouse gas, but with oxygen it reacts to form CO2, a less effective greenhouse gas. Oxygen accumulation from photosynthesis resulted in the formation of an ozone layer that absorbed much of the Sun’s ultraviolet radiation, meaning unicellular organisms that reached land were less likely to die, and as a result Prokaryotes began to multiply and became better adapted to survival out of the water. These microscopic single-celled organisms have no distinct nucleus with a membrane and include bacteria. These organisms colonised the land, then along came Eukaryotes, an organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus. For a long time, the land remained barren of multicellular organisms. The supercontinent Pannotia formed around 600Ma (that is 600 million years ago) and then broke apart a short 50 million years later. Fish, the earlier vertebrates, evolved in the oceans around 530Ma. A major extinction event occurred near the end of the Cambrian period, which ended 488 Ma. Several hundred million years ago plants, probably resembling algae and fungi, started growing at the edges of the water, and then out of it. The oldest fossils of land fungi and plants date to around 480 to 460Ma, though molecular evidence suggests the fungi may have colonised the land as early as 1,000Ma and the plants 700Ma. Initially remaining close to the water’s edge, mutations and variations resulted in further colonisation of this new environment. The timing of the first animals to leave the oceans is not precisely known, but the oldest clear evidence is of arthropods on land around 450Ma, perhaps thriving and becoming better adapted due to the vast food source provided by the terrestrial plants. There is also unconfirmed evidence that arthropods may have appeared on land as early as 530Ma. The first of five great mass extinctions was the Ordovician-Silurian extinction and its possible cause was the intense glaciation of Gondwana, which eventually led to a snowball Earth where some 60% of marine invertebrates became extinct. The second mass extinction was the Late Devonian extinction, probably caused by the evolution of trees, which could have led to the depletion of greenhouse gases like CO2 or the eurotrophication, the process by which an entire body of water or parts of it, became progressively enriched with minerals and nutrients. It has also been defined as “nutrient-induced increase in phytoplankton productivity”. This meant that 70% of all species became extinct. The third mass extinction was the Permian-Triassic, or the Great Dying event, possibly caused by some combination of the Siberian Traps volcanic event, an asteroid impact, methane hydrate gasification, sea level fluctuations and a major anoxic event. In fact, either the Wilkes Land Crater in Antarctica or the Bedout structure off the northwest coast of Australia may indicate an impact connection with the Permian-Triassic extinction. But it remains uncertain whether either these or other proposed Permian-Triassic boundary craters are either real impact craters or even contemporaneous with the Permian-Triassic extinction event. This was by far the deadliest extinction ever, with about 57% of all families and 83% of all living organisms were killed. The fourth mass extinction was the Triassic-Jurassic extinction event in which almost all small creatures became extinct, probably due to new competition from dinosaurs, who were the dominant terrestrial vertebrates throughout most of the Mesozoic period. After yet another, the most severe extinction of the period around 230Ma, dinosaurs split off from their reptilian ancestors. The Triassic-Jurassic extinction event at 200Ma spared many of the dinosaurs and they soon became dominant among the vertebrates. Though some mammalian lines began to separate during this period, existing mammals were probably small animals resembling shrews. The boundary between avian and non-avian dinosaurs is not clear, but Archaeopteryx, traditionally considered one of the first birds, lived around 150Ma. The earliest evidence for evolving flowers is during the Cretaceous period, some 20 million years later around 132Ma. Then the fifth and most recent mass extinction was the K-T extinction. In 66Ma, a 10-kilometre (6.2 mile) asteroid struck Earth just off the Yucatan Peninsula, somewhere in the southwestern tip of then Laurasia and where the Chicxlub crater in Mexico is today. This ejected vast quantities of particulate matter and vapour into the air that occluded sunlight, inhibiting photosynthesis. 75% of all life, including the non-avian dinosaurs, became extinct, marking the end of the Cretaceous period and Mesozoic era.

A small African ape living around 6Ma (6 million years ago) was the last animal whose descendants would include both modern humans and their closest relatives, the chimpanzees, and only two branches of its family tree have surviving descendants. Very soon after the split, for reasons that are still unclear, apes in one branch developed the ability to walk upright. Brain size increased rapidly, and by 2Ma the first animals classified in the genus Homo had appeared. Of course, the line between different species or even genera is somewhat arbitrary as organisms continuously change over generations. Around the same time, the other branch split into the ancestors of the common chimpanzee and the ancestors of the bonobo as evolution continued simultaneously in all life forms. The ability to control fire probably began in Homo Erectus, probably at least 790,000 years ago but perhaps as early as 1.5Ma, but it is possible that the use and discovery of controlled fire may even predate Homo Erectus and fire was possibly used by the early Lower Palaeolithic. It is more difficult to establish the origin of language and it is unclear as to whether Homo Erectus could speak or if that capability had not begun until Homo sapiens. As brain size increased, babies were born earlier, before their heads grew too large to pass through the pelvis. As a result, they exhibited more plasticity and thus possessed an increased capacity to learn and required a longer period of dependence. Social skills became more complex, language became more sophisticated and tools became more elaborate. This contributed to further cooperation and intellectual development. Modern humans are believed to have originated around 200,000 years ago or earlier in Africa as the oldest fossils date back to around 160,000 years ago. The first humans to show signs of spirituality are the Neanderthals, usually classified as a separate species with no surviving descendants. They buried their dead, often with no sign of food or tools. But evidence of more sophisticated beliefs, such as the early Cro-Magnon cave paintings, probably with magical or religious significance, did not appear until 32,000 years ago. Cro-Magnons also left behind stone figurines such as Venus of Willendorf, probably also signifying religious belief. By 11,000 years ago, Homo sapiens had reached the southern tip of South America, the last of the uninhabited continents, except for Antarctica which remained undiscovered until 1820 AD). Tool use and communication continued to improve, and interpersonal relationships became more intricate. Throughout more than 90% of its history, Homo sapiens lived in small bands as nomadic hunter-gatherers. It has been thought that as language became more complex, the ability to remember as well as to communicate information resulted so ideas could be exchanged quickly and passed down the generations. Cultural evolution quickly outpaced biological evolution and history proper began. It seems that between 8,500BC and 7,000BC, humans in the Fertile Crescent area of the Middle East began the systematic husbandry of plants and animals, so true agriculture began This spread to neighbouring regions, and developed independently elsewhere until most Homo sapiens lived sedentary lives in permanent settlements as farmers. It was also found that those civilisations which did adopt agriculture, the relative stability and increased productivity provided by farming allowed the population to expand. Not all societies abandoned nomadism, especially those in the isolated areas of the globe that were poor in domesticable plant species, such as Australia. Agriculture had a major impact; humans began to affect the environment as never before. Surplus food allowed a priestly or governing class to arise, followed by an increasing division of labour which led to Earth’s first civilisation at Sumer in the Middle East, between 4,000BC and 3,000BC. Additional civilisations quickly arose in ancient Egypt, at the Indus River valley and in China. The invention of writing enabled complex societies to arise, record-keeping and libraries served as a storehouse of knowledge and increased the cultural transmission of information. Humans no longer had to spend all their time working for survival, enabling the first specialised occupations, like craftsmen, merchants and priests. Curiosity and education drove the pursuit of knowledge and wisdom, and various disciplines, including science, albeit in a primitive form, arose. This in turn led to the emergence of increasingly larger and more complex civilisations, such as the first empires, which at times traded with one another, or fought for territory and resources. By around 500BC there were more advanced civilisations in the Middle East, Iran, India, China, and Greece, at times expanding, other times entering into decline. In 221BC, China became a single polity, this being an identifiable political entity, a group of people who have a collective identity and who are organised by some form of institutionalised social relations, having the capacity to mobilise resources. They would grow to spread its culture throughout East Asia and it has remained the most populous nation in the world. During this period, famous Hindu texts known as Vedas came in existence in Indus Valley civilisation. They developed in warfare, arts, science, mathematics as well as in architecture. The fundamentals of Western civilisation were largely shaped in Ancient Greece, with the world’s first democratic government and major advances in philosophy as well as science. Ancient Rome grew with law, government, and engineering and then the Roman Empire was Christianised by Emperor Constantine in the early 4th century but then the Roman Empire declined by the end of the 5th century. Beginning with the 7th century, the Christianisation of Europe began. In 610AD Islam was founded and quickly became the dominant religion in Western Asia. The ‘House of Wisdom’ was established in the Abbasid era of Baghdad and Iraq. It is considered to have been a major intellectual centre during the Islamic Golden Age, where Muslim scholars in Baghdad as well as Cairo flourished from the ninth to the thirteenth centuries until the Mongol sack of Baghdad in 1258AD. Meanwhile in 1054AD the Great Schism between the Roman Catholic Church and the Eastern Orthodox Church led to the prominent cultural differences between Western and Eastern Europe. In the 14th century, the Renaissance began in Italy with advances in religion, art, and science. At that time the Christian Church as a political entity lost much of its power. In 1492AD, Christopher Columbus reached the Americas, thus initiating great changes to the New World. European civilisation began to change beginning in 1500AD, leading to both the Scientific and Industrial revolutions. The European continent began to exert political and cultural dominance over human societies around the world, a time known as the Colonial era. Then in the 18th century a cultural movement known as the Age of Enlightenment further shaped the mentality of Europe and contributed to its secularisation. From 1914 to 1918 and 1939 to 1945, nations around the world were embroiled in World Wars. Following World War I, the League of Nations was a first step in establishing international institutions to settle disputes peacefully. After failing to prevent World War II, mankind’s bloodiest conflict, it was replaced by the United Nations and after that war, many new states were formed, declaring or being granted independence in a period of decolonisation.The democratic capitalist United States and the socialist Soviet Union became the world’s dominant super-powers for a time and they held an ideological, often violent rivalry known as the Cold War until the dissolution of the latter. In 1992, several European nations joined in the European Union and as transportation and communication has improved, both the economies and political affairs of nations around the world have become increasingly intertwined. However, this globalisation has often produced both conflict and cooperation. As we continue in this beautiful world though, we are at present having to cope with a world-wide pandemic for which no cure has yet been found. We are researching and looking for vaccines that it is said will at least reduce the adverse effects of Covid-19, however many do not believe that these same vaccines are what we need. As a result, a great many deaths are still being reported in countries right across our world. Some say it is a man-made virus, others are suggesting conspiracy theories, but I feel sure that just as in the past other viruses have been beaten, this one will also be. However, in the meantime we should surely behave responsibly and work together to help reduce the spread of this virus, no matter what our thoughts, ideas or beliefs may be. So that in years to come, others may then look back and learn, in order for all life on Earth to continue.

This week, a simple quote…

“The purpose of life is a life of purpose.”
~ Robert Byrne (22 May 1930 – 06 December 2016)

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I try not to spend too much time looking back on my life, but there are times when it is good to do so and I have been reminded of a blog post I sent out early last year. A few years ago now a good friend sent me an article about a daughter learning about Darwin’s Theory of Evolution and then her mother telling her about the Sanskrit Avatars, which tell their version on the beginning of life here on Earth. I appreciated that, but to me there are other people, for example the Aborigines, also the American Indians who all have their traditions. Whatever way is right, however things occurred, I really do believe that this world, along with the rest of the Universe, didn’t just happen by accident. With looming discrepancies about the true age of the universe, scientists have taken a fresh look at the observable, expanding universe and have now estimated that it is almost 14 billion years old, plus or minus 40 million years. Considering that as well as our sun, our star, there are around 100,000 million stars in just the Milky Way alone, our Earth is a bit small! As well as that, there are an estimated 500 billion galaxies. With all the fighting and killing that we humans have done in the (extremely relatively) short time that we have been around, it is perhaps a good thing that the nearest star system to our sun is Alpha Centauri, which is 4.3 light-years away. That’s about 25 trillion miles (40 trillion kilometres) away from Earth – nearly 300,000 times the distance from the Earth to the Sun. In time, about 5 billion years from now, our sun will run out of hydrogen. Our star is currently in the most stable phase of its life cycle and has been since the birth of our solar system, about 4.5 billion years ago and once all the hydrogen gets used up, the sun will grow out of this stable phase. But what about our Earth. In my blog post last week I said about what might happen if we were to take an imaginary quick jaunt through our solar system in the potential ‘last days’ of the sun. There has been speculation, there have been films, tv series, all giving a view on how things were or might be. The film ‘2001 A Space Odyssey’ is just one example. Others films like Star Trek have imagined where beings from other worlds colonised Earth, some have considered life if another race were to change life completely here. A favourite of mine, Stargate, started out as a film and then became a series where the Egyptian ruler, Ra, travelled via a star-gate to a far-distant world where earth-like creatures lived. We can speculate and wonder, it is a thing that we humans can do. Though if you know of the late, great Douglas Adams and his tales, we should not panic. Just remember that in his writings, at one point the Earth was destroyed to make way for a hyperspace bypass and that just before that happened, the dolphins left Earth and as they did so, they sent a message saying “So long, and thanks for all the fish”. But I digress. I cannot possibly detail the full history of our Earth here, but I can perhaps highlight a few areas and I shall do my best.

Many attempts have been made over the years to comprehend the main events of Earth’s past, characterised by constant change and biological evolution. There is now a geological time scale, as defined by international convention, which depicts the large spans of time from the beginning of the Earth to the present and its divisions chronicle some definitive events of Earth history. Earth formed around 4.54 billion years ago, approximately one-third the age of the Universe, by accretion – this being the growth or increase by the gradual accumulation of additional layers or matter. It came from the solar nebula. Volcanic outgassing probably created the primordial atmosphere and then the ocean, but the early atmosphere contained almost no oxygen. Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. Whilst the Earth was in its earliest stage, a giant impact collision with a planet-sized body named Theiais is thought to have formed the Moon. Over time, the Earth cooled, causing the formation of a solid crust, and allowing liquid water on the surface. The Hadean eon represents the time before a reliable fossil record of life, it began with the formation of the planet and ended 4 billion years ago. The following Archean and Proterozoic eons produced the beginnings of life on Earth and its earliest evolution. The succeeding eon was divided into three eras, which brought forth arthropods, fishes, and the first life on land, the next which spanned the rise, reign, and climactic extinction of the non-avian dinosaurs and the following one which saw the rise of mammals. Recognisable humans emerged at most 2 million years ago, a vanishingly small period on the geological scale. The earliest undisputed evidence of life on Earth dates from at least 3.5 billion years ago after which a geological crust started to solidify. There are microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia and other early physical evidence of a biogenic substance is graphite found in 3.7 billion-year-old rocks discovered in southwestern Greenland. Photosynthetic organisms appeared between 3.2 and 2.4 billion years ago and began enriching the atmosphere with oxygen. Life remained mostly small and microscopic until about 580 million years ago, when complex multicellular life arose. This developed over time and culminated in the Cambrian Explosion about 541 million years ago. This sudden diversification of life forms produced most of the major algae, fungi, and plants known today, and divided the Proterozoic eon from the Cambrian Period of the Paleozoic Era. It is estimated that 99 percent of all species that ever lived on Earth, over five billion have become extinct and estimates on the number of Earth’s current species range from 10 million to 14 million, of which about 1.2 million are documented, but over 86 percent have not been described. However, it was recently claimed that 1 trillion species currently live on Earth, with only one-thousandth of one percent described. The Earth’s crust has constantly changed since its formation, as has life since its first appearance. Species continue to evolve, taking on new forms, splitting into daughter species, or going extinct in the face of ever-changing physical environments. The process of plate tectonics continues to shape the Earth’s continents and oceans and the life which they harbour.

So the history of Earth is divided into four great eons, starting with the formation of the planet. Each eon saw the most significant changes in Earth’s composition, climate and life. Each eon is subsequently divided into eras, which in turn are divided into periods and which are further divided into epochs. In the Hadean eon, the Earth was formed out of debris around the solar protoplanetary disk. There was no life, temperatures were extremely hot, with frequent volcanic activity and hellish-looking environments, hence the eon’s name which comes from Hades. Possible early oceans or bodies of liquid water appeared and the Moon was formed around this time, probably due to a collision into Earth by a protoplanet. In the next eon came the first form of life, with some continents existing and an atmosphere is composing of volcanic and greenhouse gases. Following this came early life of a more complex form, including some forms of multicellular organisms. Bacteria began producing oxygen, shaping the third and current of Earth’s atmospheres. Plants, later animals and possibly earlier forms of fungi formed around that time. The early and late phases of this eon may have undergone a few ’Snowball Earth’, periods, in which all of the planet suffered below-zero temperatures. A few early continents may have existed in this eon. Finally complex life, including vertebrates, begin to dominate the Earth’s ocean in a process known as the Cambrian Explosion. Supercontinents formed but later dissolved into the current continents. Gradually life expanded to land and more familiar forms of plants, animals and fungi began to appear, including insects and reptiles. Several mass extinctions occurred though, amongst which birds, the descendants of non-avian dinosaurs, and more recently mammals emerged. Modern animals, including humans, evolved at the most recent phases of this eon.

The standard model for the formation of our Solar System, including the Earth, is the Solar Nebula hypothesis. In this model, the Solar System formed from a large, rotating cloud of interstellar dust and gas, composed of hydrogen and helium created shortly after the Big Bang some 13.8 billion years ago and heavier elements ejected by supernovae. At about 4.5 billion years the nebula began a contraction that may have been triggered by a shock wave from a nearby supernova, which would have also made the nebula rotate. As the cloud began to accelerate, its angular momentum, gravity and inertia flattened it into a protoplanetary disk that was perpendicular to its axis of rotation. Small perturbations due to the collisions and the angular momentum of other large debris created the means by which kilometre-sized protoplanets began to form, orbiting the nebular centre. Not having much angular momentum it collapsed rapidly, the compression heating it until the nuclear fusion of hydrogen into helium began. After more contraction, a ’T Tauri’ star ignited and evolved into the Sun. Meanwhile, in the outer part of the nebula gravity caused matter to condense around density perturbations and dust particles, and the rest of the protoplanetary disk began separating into rings. In a process known as runaway accretion, successively larger fragments of dust and debris clumped together to form planets. Earth formed in this manner about 4.54 billion years ago and was largely completed within 10 to 20 million years. The solar wind of the newly formed T Tauri star cleared out most of the material in the disk that had not already condensed into larger bodies. The same process is expected to produce other accretion disks around virtually all newly forming stars in the universe, some of which yield planets. Then the proto-Earth grew until its interior was hot enough to melt the heavy metals and having higher densities than silicates, these metals sank. This so-called ‘iron catastrophe’ resulted in the separation of a primitive mantle and a metallic core only 10 million years after the Earth began to form, producing the layered structure of Earth and setting up the formation of its magnetic field.

This Earth is often described as having had three atmospheres. The first atmosphere, captured from the solar nebula, was composed of lighter elements from the solar nebula, mostly hydrogen and helium. A combination of the solar wind and Earth’s heat would have driven off this atmosphere, as a result of which the atmosphere was depleted of these elements compared to cosmic abundances. After the impact which created the Moon, the molten Earth released volatile gases; and later more gases were released by volcanoes, completing a second atmosphere rich in greenhouse gases but poor in oxygen. Finally, the third atmosphere, rich in oxygen, emerged when bacteria began to produce oxygen. The new atmosphere probably contained water vapour, carbon dioxide, nitrogen, and smaller amounts of other gases. Water must have been supplied by meteorites from the outer asteroid belt also some large planetary embryos and comets may have contributed. Though most comets are today in orbits farther away from the Sun than Neptune, some computer simulations show that they were originally far more common in the inner parts of the Solar System. As the Earth cooled, clouds formed, rain created the oceans and recent evidence suggests the oceans may have begun forming quite early. At the start of the Archean eon, they already covered much of the Earth. This early formation has been difficult to explain because of a problem known as the ‘faint young sun’ paradox. Stars are known to get brighter as they age, and at the time of its formation the Sun would have been emitting only 70% of its current power. Thus, the Sun has become 30% brighter in the last 4.5 billion years. Many models indicate that the Earth would have been covered in ice and a likely solution is that there was enough carbon dioxide and methane to produce a greenhouse effect. The carbon dioxide would have been produced by volcanoes and the methane by early microbes whilst another greenhouse gas, ammonia, would have been ejected by volcanos but quickly destroyed by ultraviolet radiation. One of the reasons for interest in the early atmosphere and ocean is that they form the conditions under which life first arose. There are many models, but little consensus, on how life emerged from non-living chemicals; chemical systems created in the laboratory fall well short of the minimum complexity for a living organism. The first step in the emergence of life may have been chemical reactions that produced many of the simpler organic compounds, including nuclei and amino acids that are the building blocks of life. An experiment in 1953 by Stanley Miller and Harold Urey showed that such molecules could form in an atmosphere of water, methane, ammonia and hydrogen with the aid of sparks to mimic the effect of lightning. Although atmospheric composition was probably different from that used by Miller and Urey, later experiments with more realistic compositions also managed to synthesise organic molecules. Additional complexity could have been reached from at least three possible starting points, these being self-replication, an organism’s ability to produce offspring that are similar to itself, metabolism, its ability to feed and repair itself and external cell membranes, which allow food to enter and waste products to leave, but exclude unwanted substances. The earliest cells absorbed energy and food from the surrounding environment. They used fermentation, the breakdown of more complex compounds into less complex compounds with less energy, and used the energy so liberated to grow and reproduce. Fermentation can only occur in an oxygen-free) environment. The evolution of photosynthesis made it possible for cells to derive energy from the Sun. Most of the life that covers the surface of the Earth depends directly or indirectly on photosynthesis. The most common form, oxygenic photosynthesis, turns carbon dioxide, water, and sunlight into food. It captures the energy of sunlight in energy-rich molecules, which then provide the energy to make sugars. To supply the electrons in the circuit, hydrogen is stripped from water, leaving oxygen as a waste product. Some organisms, including purple bacteria and green sulphur bacteria, use an an oxygenic form of photosynthesis that uses alternatives to hydrogen stripped from water as electron donors, such as hydrogen sulphide, sulphur and iron. Such organisms are restricted to otherwise inhospitable environments like hot springs and hydrothermal vents. The simpler form arose not long after the appearance of life. At first, the released oxygen was bound up with limestone, iron and other minerals. The oxidised iron appears as red layers in geological strata which are called banded iron formations. When most of the exposed readily reacting minerals were oxidised, oxygen finally began to accumulate in the atmosphere. Though each cell only produced a minute amount of oxygen, the combined metabolism of many cells over a vast time transformed Earth’s atmosphere to its current state. This was Earth’s third atmosphere. Some oxygen was stimulated by solar ultraviolet radiation to form ozone, which collected in a layer near the upper part of the atmosphere. The ozone layer absorbed, and still absorbs, a significant amount of the ultraviolet radiation that once had passed through the atmosphere. It allowed cells to colonise the surface of the ocean and eventually the land. Without the ozone layer, ultraviolet radiation bombarding land and sea would have caused unsustainable levels of mutation in exposed cells. Photosynthesis had another major impact. Oxygen was toxic; much life on Earth probably died out as its levels rose in what is known as the oxygen catastrophe. Resistant forms survived and thrived, and some developed the ability to use oxygen to increase their metabolism and obtain more energy from the same food. The Sun’s natural evolution has made it progressively more luminous during the Archean and Proterozoic eons and the Sun’s luminosity increases 6% every billion years. As a result, the Earth began to receive more heat from the Sun in the Proterozoic eon. However, the Earth did not get warmer. Instead, geological records suggest that it cooled dramatically during the early Proterozoic. Glacial deposits found in South Africa based on paleo-magnetic evidence suggest they must have been located near the equator. Thus, this glaciation, known as the Huronian glaciation, may have been global. Some scientists suggest this was so severe that the Earth was frozen over from the poles to the equator, a hypothesis called Snowball Earth. The Huronian ice age might have been caused by the increased oxygen concentration in the atmosphere, which caused the decrease of methane (CH4) in the atmosphere. Methane is a strong greenhouse gas, but with oxygen it reacts to form CO2, a less effective greenhouse gas. When free oxygen became available in the atmosphere, the concentration of methane could have then decreased dramatically, enough to counter the effect of the increasing heat flow from the Sun. However, the term Snowball Earth is more commonly used to describe later extreme ice ages during the Cryogenian period. There were four periods, each lasting about 10 million years, between 750 and 580 million years ago, when the earth is thought to have been covered with ice apart from the highest mountains, and average temperatures were about −50°C (−58°F). The snowball may have been partly due to the location of the supercontinent straddling the Equator. Carbon dioxide combines with rain to weather rocks to form carbonic acid, which is then washed out to sea, thus extracting the greenhouse gas from the atmosphere. When the continents are near the poles, the advance of ice covers the rocks, slowing the reduction in carbon dioxide, but in the Cryogenian the weathering of that supercontinent was able to continue unchecked until the ice advanced to the tropics. The process may have finally been reversed by the emission of carbon dioxide from volcanoes or the destabilisation of methane gas.

I think that sets the basic scene for the Earth itself, but there is still much to write about in terms of colonisation of land, extinctions and human evolution. But I think this is more than enough for now. Change has continued at a rapid pace and along with technological developments such as nuclear weapons, computers, genetic engineering and nanotechnology there has been economic globalisation, spurred by advances in communication and transportation technology which has influenced everyday life in many parts of the world. Cultural and institutional forms such as democracy, capitalism and environmentalism have increased influence. Major concerns and problems such as disease, war, poverty and violent radicalism along with more recent, human-caused climate-change have risen as the world population increases. In 1957, the Soviet Union launched the first artificial satellite into orbit and, soon afterwards Yuri Gagarin became the first human in space. The American, Neil Armstrong, was the first to set foot on another astronomical object, the Moon. Unmanned probes have been sent to all the known planets in the Solar System, with some, such as the two Voyager spacecraft having left the Solar System. Five space agencies, representing over fifteen countries, have worked together to build the International Space Station. Aboard it, there has been a continuous human presence in space since 2000. The World Wide Web became a part of everyday life in the 1990s, and since then has become an indispensable source of information in the developed world. I have no doubt that there will be much more to find, learn, discover and develop.

This week, as we begin a new year…
When attempting to remember the order of planets in our Solar System, I have found they can be remembered by:
‘My Very Educated Mother Just Served Us Nachos’

Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune

(Pluto was first discovered in 1930 and described as a planet located beyond Neptune, but following improvements in technology, in 2006 it was then reclassified as a ‘dwarf planet’ in 2006.)

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