At first glance, human evolution seems to be at a standstill. If we evolved from apes a few million years ago, why are we suddenly stuck the way we are presently, with no major changes occurring in the human race for an extended period of time?
Today I read an article written by Dr Ian Rickard from the University of Durham in which he explained why this could never be the case. He argued that evolution is something that can never end because animals will always be adapting to their changing habitats. These changes are caused by alleles (differences in genes) which occur over a cumulative number of years/decades/centuries to produce evolution in genetic code, which in turn leads to evolution within species.
Evolution can often be mistaken with natural selection (when genes ‘survive, thrive and multiply’ over time to create new characteristics in a species); however, both natural selection and evolution have worked together over millennia to produce the world’s most dominant species: humans.
Some argue that humans no longer experience evolution because since the industrial revolution, we have been living longer and more healthy lives with an ever-reducing fertility rate- this is known as a demographic transition. Natural selection still occurs; for example people still experience cancer and there are genetic variations in our population. But we must still be evolving due to the issue of child mortality- those who are unfit do not survive and cannot reproduce in adulthood. This eliminates illnesses and deformities from our population.
Furthermore, people are having children later in life and over time our bodies may start accounting for this- that would be a sign that evolution is taking place within the human race. On top of this, in the past twins were unlikely to survive because they are often smaller than single babies; however, nowadays they are extremely likely to survive and these twins are much more likely to have twins than anyone else, so over time twins have become more and more common to essentially become a ‘normal’ phenomenon within our lives.
An important and reasonably recent example of evolution in humans is when we became able to drink milk as adults. Almost no other species on Earth does this, but years ago people who could drink with without having an intolerance were at an advantage as they had an additional food source. People with this allele were then more readily able to reproduce and spread their genes, leading to most adults being able to drink milk in modern times.
The author describes evolution as a ‘march with no end’ due to humans’ intrinsic relationship with it. Without changes made because of evolution, we would not be here today, and without the changes that will consequently be made in the future, the next few generations will not be around to see the world.
Keep your eyes peeled for my next post,