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A New Look at Animal Evolution
By Adam D.A. Manning (@AdamManning)
The evolution of life is an endlessly fascinating subject to study. The richness of the ever-changing chronicle of living things is part of the beauty of nature and in recent decades a new approach to viewing the evolution of the terrestrial vertebrates (that is the reptiles, birds, and mammals) has emerged which challenges our conventional categories.
Reptiles, birds, and mammals have long been the three main groupings of backboned animals that fully live on (or above in the case of birds) the land. This is derived from our everyday observations of these animals as they are today, but the fossil record reveals a somewhat different tale.
The earliest reptiles evolved from their amphibian ancestors between 310 and 320 million years ago, in the late Carboniferous period. Shortly after the emergence of the reptiles (known as the sauropsids), a new group called the synapsids evolved from them, splitting the amphibians’ descendants in two.
For a while this divergence seemed to be favouring the synapsids. This is the group of animals that includes mammals (and therefore humans as well), but it also includes a varied assemblage of all sorts of other species. The earlier synapsids included the familiar Dimetrodon, which had a large “sail” on its back and was roughly four metres long. It was a top predator for its time, that being the early Permian period and animals like Dimetrodon later evolved into the therapsids.
Therapsids were a very diverse group of animals, such as Lystrosaurus from the early Triassic, which became one of the most successful vertebrate land animals of all time. Another remarkable species from the later Triassic was Lisowicia, one of the most massive animals of its time, comparable in size to an elephant. The ancestors of the mammals within the therapsids were in a group called the cynodonts, which included the fearsome wolf-sized predator Cynognathus, again from the Triassic.
Whilst the synapsids seemed the more dominant since diverging from their more reptilian ancestors, something was happening to challenge that dominance during the Triassic. The sauropsids were diversifying into all sorts of new types, including the dinosaurs and the crocodylomorphs, that is the crocodiles and all their ancestors. Crocodiles and the group they belong to have been an enormously successful family of animals, with an abundant range of all manner of different types, far more than those we are familiar with today. There were also numerous aquatic types within the sauropsids, such as the dolphin like ichthyosaurs, and flying and gliding species as well.
The catastrophic extinction event at the end of the Permian and the start of the Triassic is well known as causing the extinction of a significant majority of all species. There was another, albeit less cataclysmic, extinction event at the end of the Triassic and start of the Jurassic, roughly 200 million years ago. The Triassic-Jurassic extinction saw the demise of all the therapsids apart from the mammal-like cynodonts.
The Jurassic period and the Cretaceous that followed it saw the sauropsids in the ascendant, causing the Mesozoic to often be referred to as the Age of the Dinosaurs. Whilst the therapsids were limited to those cynodonts that had survived, they went onto evolve into a great many diverse species, including the true mammals and their ancestors.
Mesozoic mammals and their relatives are often thought of as small, unobtrusive shrew or mouse like animals, and many were. Yet here too, there was a surprising divergence of body types. These included tree-climbers, species that glided and animals that had a burrowing lifestyle, like moles. Another extraordinary Jurassic animal from this group was the beaver-like Castorocauda, which was adapted for living partially in the water, and had a pelt of fur. One of the largest Mesozoic mammals was the Cretaceous carnivore Repenomamus, and there is evidence that it ate dinosaurs.
For all this mammalian diversity, there is no doubt that the sauropsids dominated throughout the Jurassic and the Cretaceous. The mass extinction at the end of the Cretaceous that included all the non-avian dinosaurs was only a temporary setback as the birds, as descendants of the dinosaurs and part of the sauropsids, not only survived but went on to thrive.
Including the birds, there are today more species of sauropsids than synapsids. Whilst it is tempting to think of the time after the Mesozoic as an age of mammals, it is perhaps more valid to think of it as a continuation of the age of sauropsids, just as it has been for the last 200 million years or so. At a personal level, most of the wild animals most people will see are sauropsids, rather than synapsids. The reptiles and birds we see today are really part of the sauropsids, whilst the mammals, including us, are the only survivors of a much larger group, the synapsids.
The fossil record helps us to understand the story of life in all its richness and can often challenge preconceptions based on our snapshot of living things as they are today, showing us new relationships and connections and enhancing and deepening our appreciation and love of the natural world.
Posted in The Science-Minded Citizen Tagged birds, dimetrodon, Evolution, mammals, reptiles, synapsids Leave a comment
The Facts About Theories
By Adam D.A. Manning (@AdamManning)
“Evolution is just a theory”, we sometimes hear, disapprovingly muttered.
“Climate change, it’s just a theory”, it is said, as if that was enough to stop the flood of evidence about our changing climate.
Calling something “just a theory” is often used as an easy way to belittle science. Referring to theories in this way makes it sound as though they are flimsy nonsense, easily rebutted and not to be taken seriously. Is that really the case?
Inevitably when discussing the meaning of words, it can be easy to descend into wordplay. The definition of a word changes over time and ultimately depends on the way it is used. At any point in time, one word may also have several different usages and the differences between them may be rather subtle.
In the scientific context in which we are interested, “theory” has quite a precise usage. “Theories”, the paleontologist Stephen Jay Gould wrote, “are structures of ideas that explain and interpret facts” (1). An established scientific theory will have been rigorously scrutinized and will form part of the body of knowledge. It will be a concept that is generally accepted and recognized.
That said, there is nothing immutable or invulnerable about a scientific theory. Einstein’s theory of gravitation has replaced Newton’s (although Newton’s is still good for most practical purposes). Indeed, even facts are not certainties either, but both make up elements of our knowledge of the world through science.
To say “it’s just a theory” about evolution, gravity or climate change is misinformed and lazy. To deride theories in this way is a much used and thoughtless denigration of science that often conceals an attack on a naturalistic outlook on the world, as if scientific knowledge is arbitrary and of little value.
This attitude is regularly accompanied by either a misleadingly innocent disregard or a surprising unawareness of the profound influence and power science has in our lives; from the practical, such as the technology we routinely use, or the medicine we take, to the astonishing and wondrous, in providing us with our understanding of the universe, from the most microscopic to the grand view of all that we can observe. Far from being “just a theory”, scientific theories are instead hard-fought-for knowledge, without which modern society would be impossible and our lives immeasurably poorer, both physically and mentally.
(1) Stephen Jay Gould, Evolution as Fact and Theory, 1981.
Posted in The Science-Minded Citizen Tagged einstein, Evolution, scientific, stephen jay gould, Theory 4 Comments
Standing Up for Sexual Selection in Human Evolution
Evolution by natural selection as set out in Charles Darwin’s On the Origin of Species from 1859 is often thought of as a constant and bloody struggle for survival. Here, living organisms are engaged in an incessant fight to survive long enough to reproduce and over the long stretches of geological time, species adapt to their environment so as to enhance their prospects of leaving descendants. Those that don’t leave descendants become extinct.
This view of evolution as red in tooth and claw mischaracterizes the totality of Darwin’s thought. In the Origin of Species, Darwin briefly refers to what he calls sexual selection, which he refers to as not “a struggle for existence, but on a struggle between the males for possession of the females”. The peacock is perhaps the clearest example of the concept with its beautiful tail feathers, which it flourishes to attract the attention of a peahen. Its beauty aside, the peacock’s tail must be an ungainly hindrance to the bird in its daily life; its length when trailing on the ground and visibility when displayed must make it easier for a predator to catch. If evolution was just a struggle to survive, why did the peacock have such an impediment to its chances of survival?
So striking was the example of the peacock in suggesting that there was more to evolution than just a struggle for existence that in 1860, Darwin wrote, “[T]he sight of a feather in a peacock’s tail, whenever I gaze at it, makes me sick!” Peacocks and other examples of such displays lead to Darwin developing his ideas on sexual selection in a later volume entitled The Descent of Man, and Selection in Relation to Sex in 1871, yet this aspect of his theory of evolution has never received the same degree of attention as the concept of natural selection by adaptation, in part due to resistance by some of his original supporters.
Birds offer some of the most obvious illustrations of the concept, including the birds of paradise with their extraordinary plumage, saturated in colour. Bowerbirds are another striking example. Male bowerbirds make great efforts to create elaborate bowers, or nests, ornamented with stones, shells and even human debris such as bits of plastic. The females inspect them and, after a number of visits to different bowers, elect to mate with the male they deem to have created the best.
These characteristics do not directly assist in survival except in the limited sense of attracting a mate. If the characteristic leads to an increase in opportunities to mate that outweighs the risks in additional visibility to predators, it assists in the species’ survival.
Sexual selection plays a role in mammal courtship as well. In many species, the larger a male is, the more likely he is to mate. Females generally choose larger males to mate with, presumably on the basis that larger babies are more likely to survive, dominate others and then mate in turn. Male characteristics that suggest larger size add to their attractiveness to females. Male koalas and hyenas, for example, give out bellows and barks to attract a mate and it seems the deeper the sound, the more attractive it is to females as this suggests a larger male.
In deer, sheep and cattle, the males grow horns or antlers, which can be large and unwieldy. The larger the antlers or horns, the more likely the male animal is to mate. This illustrates how such characteristics can become so pronounced; a feedback loop sets in whereby the females chose to mate with the male with the largest antlers, the best bower and so forth and so males are born which inherit that characteristic. The modification is selected for across the generations, becoming more pronounced.
It is fascinating to consider human evolution from this perspective. The most profound aspect of human evolution, the factor that really defines what it is to be human, is being bipedal. No other primate, or indeed mammal, has the same bipedal form of locomotion that we do. It is possible that the emergence of our higher level of intelligence is only as a consequence of first becoming fully bipedal.
Full bipedalism in our human ancestors followed the divergence between humans and chimpanzees from a common ancestor, around six million years ago. A number of theories have been suggested for why our ancestors became fully bipedal and one of the first was that climatic changes in Africa lead to the opening up of savannas and the reduction in forests. As a consequence, our human ancestors descended from their formerly arboreal habitats, spent more time on the ground and, as a result, became bipedal from striding around their new habitat.
Yet paleoclimatic evidence suggests this environmental change, if it occurred, did not happen around the time that fossil evidence points to bipedalism developing. Other theories include the idea that being upright allows humans to be cooler as more of their body is higher off ground level and also decreases the amount of body area that is directly exposed to the sun. This regulatory control offered advantages in maintaining body temperature and an increased chance of survival.
It is also possible that partial bipedalism is a characteristic of our older ancestors, including the joint ancestors of chimpanzees and humans, and that chimpanzees are the ones that have changed the most by becoming functionally quadrupedal. Gibbons, for example, are often bipedal when climbing in trees and walking along thin branches and provide an illustration of the nature of our possible original partial bipedalism. According to this theory, human ancestors were already partially bipedal when living an arboreal lifestyle and perfected this when travelling on ground level, whilst chimpanzees took a different course.
The fossil record for human ancestors is far from complete and it is challenging to draw a conclusion from it that definitively establishes why our ancestors became fully bipedal. This is especially so if the reasons for this were primarily behavioural as it is likely that this will have to be inferred from the fossil evidence.
Bipedalism has a number of disadvantages to humans compared to our quadrupedal great ape relatives. Most significantly, it makes childbirth more difficult and dangerous for both mother and baby. It also makes humans more susceptible to back and knee problems and meant that our ancestors sacrificed the foot’s opposable “thumb” and its ability to grasp objects.
If standing and walking upright has such significant drawbacks, it might be as a result of factors that are not directly related only to survival. This suggests that our bipedal gait is due to sexual selection instead, at least in part. Sexual selection can radically alter an organism’s form and behaviour, as it did with the peacock, so it is not out of the question.
Richard Dawkins has suggested that it might be as simple as that – standing upright became an attractive trait at some point amongst our ancestors. In his book The Ancestor’s Tale: A Pilgrimage to the Dawn of Life he suggests that at some point in our evolution, those who engaged in the new “fashion” of standing and walking on two legs were attractive to potential mates, gained reproductive success and left descendants whereas, over time, those who weren’t bipedal failed to mate. As described above, this trait could quickly become established and grow more and more pronounced as the generations passed by. At least initially, the practical utility of being bipedal may have been irrelevant.
Standing upright might have also been important in terms of sexual selection as being bipedal helps in displaying the body to potential mates. An example of such a display could be human female breasts, which are larger than those of other primates. Chimpanzee breasts are flatter unless they happen to be lactating, in which they are enlarged to store milk. Human breasts are permanently in this larger condition and it is possible this is a display to attract a mate. If so, this would be an unusual example of a female displaying to attract a mate. Standing upright helps display the breasts more easily.
Similarly, it has been suggested that standing upright helps the male display his genitals to females. Dawkins has elaborated on this point by noting that male humans, unlike other great apes, lack a penis bone or baculum. An erection in the human penis is entirely due to blood pressure and Dawkins suggests that the lack of a baculum has evolved so that the erect penis can act as an indicator to a potential mate of both physical and mental health. This might seem speculative, but points such as these are potentially fundamental to human reproductive success and so could have played an important role in our evolution.
An interesting point to consider is that human evolution may have been subject to much more randomness than either natural or sexual selection might imply. At the genetic level, evolution is due to random mutations. Given a large population and a long period of time, we can interpret changes in the organism’s form or behaviour as making it better suited to survive or attract a mate. Yet if the population is small, such changes do not have sufficient individuals to produce a pronounced difference and the random background of mutations and events can prevent natural or sexual selection from playing the role in the species’ evolution that we would normally expect.
It seems that for a long time, our human ancestors suffered from just this perilous condition. In the six million years or so since we diverged from chimpanzees, for the vast majority of the time, the line of animals that lead to the chimpanzees outnumbered our ancestors. We have, until very recently, been generally unsuccessful animals, with an insignificant population. Genetic studies of chimpanzees indicate they are more evolved animals than we are, as evolution has had more material to act upon. As a result, random mutation may be a more important factor in human evolution than we might care to think.
The transition to full may have arisen as a result of many of these factors acting together; it is unlikely that it was just one cause. For example, perhaps sexual selection started the process but when the practical advantages gave our bipedal ancestors a better chance of survival, the change really took hold. The incompleteness of the fossil record and the generally interpretative context of much of these issues suggest it is possible that there will never be a definitive answer as to how or why humans became fully bipedal. As more fossils are uncovered, more will be learned about our ancestors and our evolution and it will be fascinating to see the story unfold.
Posted in The Science-Minded Citizen Tagged bipedalism, Evolution, human, selection, sexual Leave a comment
Looking Back at the Millennium’s Eclipse
Disclaimer: Viewing a Solar Eclipse can be dangerous. Do not look directly at the Sun as this can cause pain, damage to your eyes and sight and even blindness
1999 always sounded like a momentous year growing up in the 70s and 80s; the last year with a 1 at the front (until 10,000 of course!), the last year of the nineties and the last year of the 1900s. To many people, it was also the latter bookend of the twentieth century and the second millennium for that matter; maybe 2000 was the proper terminal point, but that just didn’t sound right. 2000 sounded more like a starting point – 1999 had a finality all of its own from sheer numerical content. Prince sang a song about it and there was even a stylish science fiction TV series set in that year. The real 1999, supposedly ending in the biggest party in history, was always going to have difficulty competing with the expectation.
In England, the year 1999’s special role in letting in the Millennium included an extraordinary event that had long been predicted with total certainty – a total eclipse of the Sun, due on 11th August of that year. This momentous interplanetary interplay was entirely fitting to the times and in the long final decades of the twentieth century, the eclipse’s approach was hailed with excitement and curiosity.
A solar eclipse is the blocking of the Sun, to a lesser or greater extent, by the Moon. This only happens rarely as the Moon’s orbit is at a different angle to the plane of the Earth’s orbit around the Sun. The Moon and the Sun are almost exactly, but not quite, the same size in the sky as seen from the Earth as each other; an unusual and striking coincidence.
The Sun is roughly 400 times further away from the Earth than the Moon is. At the same time, the Sun’s diameter is roughly 400 times that of the Moon. As a result, the relative ratios of size and distance mean that they are both roughly a half of a degree in diameter across in the sky. If the situation were any different, solar eclipses would not occur in the way they do.
In fact, the Moon spends the majority of it’s time slightly too far away from the Earth to occupy exactly the same size in the sky as the Sun. As a result, slightly more solar eclipses are what is called “annular” rather than total – that is rather than blocking out the Sun’s disc entirely, the Moon can only occupy most of it but not all, leaving a ring or annulus of the Sun visible behind it.
The Moon’s distance from the Earth varies during its orbit and sometimes it is closer than usual. It is during these points that the Moon is almost exactly the same diameter in the sky as the Sun and the full total solar eclipse can take place.
The distance between the Earth and the Moon is growing over time at the rate of nearly four centimetres per year, or roughly the same speed as the rate at which fingernails grow. At this rate, it will take a very long time, perhaps in the order of a half a billion years or so, before this effect will have an appreciable difference on eclipses, but the general progression will mean more annular eclipses than total.
When, finally, Wednesday 11th August 1999 arrived, there was the dawning realisation that a solar eclipse visible in England would, inevitably, be impaired by less than perfect weather. On the day itself, a colleague and I took some time out from the office to observe it from a nearby park in Portsmouth. At the time, I took with me a hand held mini-cassette tape machine, feeling suitably proud of my technological recording mechanism, to record any such observations.
Nearly eighteen years later, for the first time I’ve gone back and listened to the tape, having to borrow a now virtually obsolete tape machine to listen to it. Such is the march of technological innovation that my ten-year old daughter has never seen a cassette tape machine, of any sort, in operation before.
Though, as an English eclipse, the cloud and modest sunshine meant the event was perhaps less cosmically impressive than it might have been, it’s clear from the tape that we found it to be an absorbing, odd and vaguely disturbing experience. There was already a diminution to the light when we entered the park at around 10.50am that morning, with a noticeable slice missing from a top corner of the Sun’s disk. As the minutes ticked by, the gloom became more profound and the wind driven clouds curled and roiled darkly across the diminished face of our star.
The park where we sat in Portsmouth has an aviary in it, in addition to the normal pigeons, crows and other birds that normally strut and flutter about. As the darkness gathered, unsettlingly the birds noticeably quietened. The absence of this normal background noise of life added to the unease that was slowly building. The light level dropped to around that of twilight, but it was twilight with a distinctively silver tone.
As the cloud whisked across the face of the Sun and Moon in their astral embrace, a shining crescent, thinly blazing, could be glimpsed every now and then. This far from the zone of totality, our eclipse was only ever going to be partial, but it was still an extraordinary sight.
As the maximum point of the eclipse, it grew colder and the wind picked up. The silver twilight, the hush of the life in the park, the gusts and the dropping temperature combined in a surprisingly disturbing, eerie experience. These points were punctuated by the firing of a cannon, presumably on the orders of the City Council, and it was easy during these moments to understand how terrifying an eclipse might have been for people of earlier ages, bereft of our clear understanding of the Solar System’s mechanics and with only their imaginations to play out on what might be happening.
Soon though, the normal daylight returned and for some minutes the rising light levels manifested as pretty and unpredicted pink and orange shades on the clouds near to where the Sun and Moon passed in the sky. Once again, all was well.
America’s eclipse on 21st August 2017 looks very promising; bisecting the United States, it is almost certain to have stretches of clear, or at least clear enough, skies for an uninterrupted total eclipse. Millions of people should be able to enjoy this extraordinary spectacle and for those of us not in the USA, it can be viewed on the NASA website at https://eclipse2017.nasa.gov/. If you can, do experience it – but keep your eyes safe!
Posted in The Science-Minded Citizen Tagged eclipse, moon, sun Leave a comment
The Age of Dinosaurs – Today
“The dinosaurs are not extinct.”
Robert T. Bakker, Paleontologist.
Imagine the dinosaurs, imperiously soaring, loftily above lowly, scurrying mammals. They are the rulers of all they survey from one horizon to the other. Is this hierarchy confined to a prehistoric scene, 100 million years ago? No. This is our world, today.
The name “dinosauria” was first used by biologist Richard Owen in 1842, at around the same time that Charles Darwin had formed his theory of natural selection. On the Origin of Species, Darwin’s seminal work beautifully describing his theory, was published in 1859. In the years immediately following publication, fossils of a particular animal were discovered that would shock scientists and add much needed evidence to the debate about evolution.
These were from southern Germany and were of a wholly unknown species. It was given the name Archaeopteryx, meaning “ancient wing” or “ancient feather”, due to the clear remains of fossilised feathers around its body. It dated from roughly the middle of the Age of Dinosaurs (referred to as the Mesozoic era).
The first fossilised skeleton of Archaeopteryx was discovered in 1861 and was so peculiar it caused a sensation. Possessing features that seemed both bird like (or avian) and reptilian, some wanted to categorise it as a type of dinosaur, while Richard Owen decided it was a bird. Biologist Thomas Huxley, nicknamed Darwin’s Bulldog due to his vocal support of natural selection, declared that it was a transitional fossil, its intermediate nature showing the evolution of birds from a dinosaur ancestor.
When On the Origin of Species was originally published, the fossil record was limited, with few, if any, notable examples of transitional species. Darwin’s reference to them is unsurprisingly guarded as a result yet Huxley and others soon trumpeted Archaeopteryx as the evidence supporting evolution that the theory’s critics said had been missing. Archaeopteryx was coupled with other striking examples from newly discovered fossils, most notably the gradual evolution of the horse in North America from small, multi-toed animals to the present much larger one toed animals. Evolution occurring through the transformation of species was becoming clearer as more fossils were uncovered.
Yet the dinosaur origin of Archaeopteryx and by extension birds, whilst popular, was not accepted by everyone in the nineteenth century and later many scientists renounced the idea. The early twentieth century saw the ascendancy of a theory that the origin of the birds lay in a more primitive family of reptiles called thecodonts (a now obsolete term) that predated dinosaurs. An apparent lack of clavicles (or collarbones) in dinosaur fossils at that point distinguished them from modern birds, which all had clavicles, and this formed the foundation for the thecodont origin theory. The thecodont origin of birds became the generally recognised wisdom on the issue until the late twentieth century. Any similarities between early birds and the smaller dinosaurs they had been compared to, such as Compsognathus, were a coincidence due to convergent evolution and nothing more.
This coincided with the prevailing popular concept of dinosaurs as large, slow, cold blooded creatures. The word “dinosaur” became an insult for anything that was behind the times, moribund and on the way to extinction. Dinosaurs were considered by some as uninteresting animals that had only lead to an evolutionary dead-end when they all died out at the end of the Mesozoic.
It is tempting to think of ideas about dinosaurs as largely being unchanging, given that they existed so long ago. Once facts are discovered about them, that must be it, we might think. Yet like all areas of science, new discoveries often lead to old ideas being challenged and a long established concept may evolve into new, fresh insight.
The sixties were a time of revolutionary thoughts in many areas, including dinosaurs. New findings concerning a relatively small carnivorous dinosaur called Deinonychus lead paleontologist John Ostrom to the conclusion that some dinosaurs, at least, had been active, energetic animals with sophisticated capabilities and not such lethargic, dull beasts after all. Further studies indicated that dinosaurs were warm blooded, like mammals and birds, and not cold blooded like other reptiles.
This revisionism went further. Ostrom noted the numerous similarities between Deinonychus and the earliest birds, including Archaeopteryx, and declared that the apparent lack of a clavicle in dinosaur fossils was an insufficient basis for rejecting the dinosaur-origin theory. Other fossils, including those of Tyrannosaurus Rex, made it clear that dinosaurs had a clavicle in any event.
This new approach was very controversial and the subject of heated debate for a number of years. Unlike On the Origin of Species, it was to be several decades before fossil evidence caught up with theory. Starting in the nineties, spectacular new fossils from the Mesozoic were uncovered in China, revealing a range of new avian species from the era. These included bird like animals that pre-dated Archaeopteryx. All of them were clearly similar to dinosaurs.
Perhaps even more shocking was the discovery of fossils of feathered dinosaurs, again from China in the 1990s. The absence of feathered dinosaurs prior to their discovery had been a point that opponents of the dinosaur-origin theory had relied upon. Their discovery strengthened the link. The presence of feathers has been discovered for a number of dinosaur species, mostly small carnivorous types belonging to the coelurosaur group (or clade), including relatives of Compsognathus and even species closely related to Tyrannosaurus Rex. Paleontologists now believe that many species of dinosaur, possibly including Tyrannosaurus Rex itself, had feathers, or feather-like, coverings.
With this new wealth of fossil evidence, many paleontologists accept that birds evolved from dinosaurs. Indeed, so close is the relationship that birds are considered to be part of the dinosaur group. Specifically, birds are part of the coelurosaur clade of dinosaurs and are the only dinosaurs that did not die out at the end of the Mesozoic, some 66 million years ago.
Two families of feathered coelurosaurs, the troodontids and the dromaeosaurids, are considered to be the closest relatives of the birds and, like all the other non-avian dinosaurs, became extinct at the end of the Mesozoic era. They are normally viewed as having evolved from the same earlier dinosaurs that gave rise to the birds themselves, in parallel with Archaeopteryx and the others. They kept their feathers but did not attain flight, unlike the avian dinosaurs. Reconstructions of these species suggest animals that were weirdly bird like, yet maintained a distinctly dinosaur, alien quality about them.
So bird like are these two families, some have suggested in fact they belong to the avian dinosaurs themselves and so are directly descended from earlier birds. In a similar way to ostriches and emus, these birds lost the ability to fly but retained their feathers. So, not only are birds really dinosaurs, some (normally considered to be non-avian) dinosaurs may have actually been birds!
Following the end of what is usually thought of as the Age of the Dinosaurs, that is 66 million years ago, birds flourished and evolved into the multiplicity of forms that we know today. Some are highly intelligent animals and all of them are superbly adapted to their environment. Of the land dwelling vertebrate animals, the birds are the most successful, having the highest number of species. They live on every continent and for every one human, it is estimated that there are roughly forty birds. It is truly the Age of the Birds.
If, as we have seen, birds are in reality dinosaurs, then the great Age of the Dinosaurs did not vanish but continues to thrive today. During the Mesozoic, mammals were generally small animals, scurrying furtively to and fro, out of the way of their dinosaur superiors. An Allosaurus, Diplodocus or Corythosaurus might march by, unimpressed by our ancestors’ existence, towering above the furry beasts.
And in our time, when we look up and spy the eagle, the pigeon or the seagull soaring serenely above our heads, occasionally deigning to look down at us scuttering about, we might wonder, perhaps with a little imagination, has anything really changed?
Posted in The Science-Minded Citizen Tagged birds, dinosaur, mammals Leave a comment
It Really Is Rocket Science
Space has long been a wonderful source of inspiration for many people. Numerous scientists and engineers have pursued careers from having the touchpaper of their imagination lit by the thrill of exploring Space, whether that be in the context of science fiction such as Buck Rogers or Star Trek or the real deal, such as the Apollo moon missions.
Even those, such as myself, who do not have a Space career can still get involved and learn more. Recently the British Interplanetary Society (BIS) held a special day of talks billed as an “Introduction to Rocket Science” which was an opportunity for the curious to hear from leading experts. The BIS is the world’s oldest space advocacy organisation and has for over eighty years looked ahead in visionary thinking about the exploration of Space.
To my delight, none other than the prestigious Royal Institution (RI) in London was the venue for this blast off into astronautics. The RI is a cherished organisation in the UK and many of us are familiar with the science-themed Christmas Lectures that are held there. The talks were held in the same lecture hall used for the Christmas Lectures, which gave proceedings a special, historical atmosphere.
As always, the BIS warmly welcomed members of the audience and prior to the launch of the event, I noted how many young children were in attendance. As a father, it is clear to me how quickly children grow up and so reaching out to them with events of this type is so important in firing their imaginations and giving them a valuable look into these areas.
The day featured a variety of presenters on all sorts of Space related topics and included some practical experiments, which reminded me vividly of the famous Christmas lectures. This included a beautiful, ultra-light model aircraft powered by a rubber band to demonstrate the principles of flight, followed later by a dramatic combustion of an alcohol-based liquid in a canister to loudly demonstrate something of the power of a real rocket engine.
Several of the speakers touched on how their careers had progressed and this included Abbie Hutty, a Senior Spacecraft Structures Engineer who is working on the ExoMars rover vehicle. In doing so, she built on the theme of reaching out to the youngsters in the audience and planting the idea in their minds that they too might one day get involved for real. She spoke compellingly about the fascination of her work and the sense of achievement.
One of the most powerful presenters at the day was Professor Chris Welch, a Fellow of the BIS. He described how hearing a talk by Carl Sagan at the RI in 1977 on the importance and urgency of the human exploration of Space had motivated him in turning his interest into his vocation. Later Professor Welch debated on a key issue for Space exploration: Are astronauts really needed or should all exploration be left to robotic missions? The view of the audience was unsurprisingly that human exploration of Space should continue.
Another star speaker was Cady Coleman, a NASA astronaut and a veteran of two Space Shuttle missions and a stay on the International Space Station. It was a special thrill to me, along with many others in the audience, to hear for the first time from someone who had been in space. Cady Coleman soon earned the gratitude of her RI audience with kind remarks about British space hero Tim Peake, referring to him as an exemplary astronaut and a gifted science communicator.
The extraordinary growth in the discovery of extrasolar planets (that is planets outside of our Solar System) was the subject of another talk. Dr Don Polacco detailed the progress in finding these, including extrasolar Earth-like planets, and noted the tendency for somewhat over-enthusiastic, if not to say inaccurate, headlines that can arise from new findings. I was particularly fascinated by his view that if we should one day be able to communicate with an extrasolar civilisation, the chances are that they would be millions or even billions of years more advanced than us.
It was an enlightening and entertaining day with a rich diversity of speakers. Hearing directly from leading academics and practitioners helps take an interest off the page and here, this feeling was bolstered by being at the RI, with its prominent role in advancing scientific knowledge. Attending events of this sort are not only a great way to learn more – they can inspire a feeling of being involved, of being an active participant ready to take further steps in an adventure into science.
Posted in The Science-Minded Citizen Tagged bis, children, education, learning, space Leave a comment