The evolution of evolution

Popular culture often gets science wrong. Evolution is no exception.

Written By: Zachary Brigden and Abbie Curd

Art By: Jo Jo Taylor.

Darwin published On the Origin of Species in 1859, shocking a world which still generally believed in creationism and a higher power. The concept of natural selection as the driving force of biological change was met with initial disbelief and, to some extent, amusement. Since then his theory has become one of science’s greatest: it is taught in school as the Holy Grail of biology and to question it is almost unheard of. What scientific discoveries in the last 150 years have led to this radical change in perspective?

For the general population, the change in attitude can be attributed to the fossil record; the whale is perhaps the best documented example. It is believed to have evolved from an organism called Pakicetus that was alive 50 million years ago. The discovery was made when Dr Gingerich, a paleontologist, found a small section of its skull in 1983. Initially it was linked to the whale lineage by its unique whale-like ear. This ear was used to reconstruct the whole organism and the computer generated image was heralded on the cover of Science, which they claimed depicted the “first whale” with a blowhole and fins.

However, in 2001 the rest of Pakicetus’ fossil was discovered. Science had got it wrong. Rather than a blowhole, the nostrils of Pakicetus were located at the end of the nose, and rather than fins it had hooves. In every possible way, Pakicetus was a land mammal, and not the whale-like mammal that the public had been led to believe.

This mistake was not an isolated one. In 1974, a world-famous fossil named Lucy (the Beatles’ song Lucy in the Sky with Diamonds was playing when it was found) was discovered and announced as an ancestor of Homo sapiens. The fossil showed ape-like claws and arms much like modern day primates. Crucial to human evolution, Lucy had the human-like anatomy of pelvis, knee and ankle bones – she could walk upright.

Museums all over the world, and even Hollywood, depicted Lucy with unshakeable faith as the archetypal early human ancestor. And yet in 1994, UCL’s Dr Fred Spoor published a paper in Nature that revealed how Lucy’s ear canal was similar to other knuckle-walking primates, as opposed to those that walk on two feet. This meant that Lucy would have found it difficult to balance and move in an upright position. To worsen matters, the fossil was found to have the same strengthened wrist anatomy as other knuckle-walking primates, providing further evidence that Lucy may not have primarily walked on two feet.

By far the greatest mystery of the fossil record is the Cambrian Explosion. It occurred around 540 million years ago and lasted between 20-25 million years, a blink of an eye in terms of Earth’s history. However, it was in this brief period of time that almost all major animal phyla appeared. Most of the general public are not aware of this significant event. Schoolchildren are taught that evolution is a build up of mutations and that natural selection leads to gradual change. Then how did this enormous diversity appear so quickly? Scientists still do not know the answer.

Some theorise that the development of eyes allowed predator and prey relationships to form, accelerating evolution. Dr Nick Lane, a reader in evolutionary biochemistry at UCL, argues that it could have been due to increasing oxygen levels as ‘fermentation causes a massive reduction in energy transfer’; the establishment of a much richer oxygen supply led to an increase in energy transfer between predators and prey, which sped up the evolutionary process.

UCL’s Dr Paola Oliveri, of the Department of Genetics, Evolution and Environment, argues that although the morphological change shown by the fossil record is sudden, genetic changes may have accumulated over a much greater time period without significant visible changes in morphology. Oliveri speculates that it is possible that one single mutation resulted in huge morphological change, made possible by the preceding mutations that had no noticeable effect. Although these theories are convincing and offer fantastic explanations for this mystery, does the Cambrian Explosion itself not defy the basic principle of Darwin’s theory that evolution is an extremely slow process? According to Dr Oliveri, evolution does not always have to occur at the same rate. In real terms, this explosion occurred over millions of years and therefore the idea of it being ‘sudden’ is not strictly true.

Clearly the topic of evolution is still widely debated among the experts; however most younger scientists are not exposed to this fascinating debate. We are given information to accept blindly, and rarely given the opportunity to speak up and question some of the facts. The story is similar for the general public. The evidence that is most accessible in museums in the form of fossils can often be misleading, such as in the case of Lucy. More complex mysteries such as the Cambrian Explosion are seldom mentioned, and even when they are there is little evidence to support the theories: is this really good enough?

We are taught that to be a scientist is to question ideas: debates and challenges to this well-established theory should be welcomed, rather than met with the same amusement that Darwin initially was. The understanding of evolution has changed hugely in recent times. Who knows what our grasp on it will be in another 150 years, with the expanding field of evolutionary genetics? Science is not dogma: we should not be scared to challenge the theories that are taught as standard and question the often not-so-reliable information that is handed to us.

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