Are humans still evolving?
The term ‘survival of the fittest’ refers to natural selection. The idea was popularised by Charles Darwin, who claimed that our species will constantly adapt to the challenges of the previous generation. But recent discussion among scientists concerns whether humans are evolving no more.
Thanks to modern advances, we’ve produced treatments for diseases that once wiped out entire populations. We know how to protect ourselves from predators and keep ourselves fed and clothed; our chances of producing healthy children are today incredibly high; we are free from so many challenges of a few hundred years ago. So is there anything we haven’t mastered that could suddenly be a major factor in our development? Or have we, as legendary broadcaster Sir David Attenborough describes, “put a halt to natural selection”?
A recent study from the universities of Sheffield and Turku in Finland suggests otherwise. It claims that despite modern housing, sanitation, medicine, falling death rates and a decreasing family sizes since the start of the industrial revolution 250 years ago, Darwin’s theory is still in effect.
The researchers looked at birth, death and marriage certificates for 10,000 people across areas in Finland, from the 18th century to the present day. Variations were discovered between individuals in terms of lifespan, family size, and the ages of first and last childbirth. People today are able to start a family later in life, which means genetic evolution may have made it easier to reproduce at an older age. This led them to conclude that cultural influences had not put an end to human evolution, and that genetics is still at work.
There are also signs of this in our everyday lives. For example, the fact that we drink milk is one indication. Historically, the gene that regulates our ability to process lactose only stayed in our bodies for a short time after birth. But by domesticating animals and drinking their milk, it has gradually become permanent, to the extent that in northern Europe, the genetic mutation for digesting milk is carried by around 95 percent of today’s population.
“Nanotechnology could manipulate molecular and atomic structures, enabling us to repair ailments and extend lifespans”
Wisdom teeth can be considered in the same vein. There was a time when human beings had a very different diet. Instead of softer foods that are easy to chew, we’d be eating roots and leaves, and pulling slabs of meat apart with our teeth, which would wear out quickly. It is thought that the wisdom teeth came last to compensate for this loss. Today we cut our food with knives and forks and, as a result, have fewer teeth and smaller jaws because there is less work to do. Wisdom teeth just aren’t needed and around 35 percent of people are now born without them, which suggests the body is already phasing them out.
An interesting area where scientists who agree that we are evolving but differ in opinion is whether we are changing for the better or worse? The ‘hygiene hypothesis’ suggests that the intense cleanliness of our modern world means we are losing the ability to fight infections. But at the same time, generations have faced so many diseases in the past and there are many we have grown resilient to. Scientists have identified genes in our bodies that fight malaria, with future generations less inclined to develop cancer or heart disease.
One of the more disturbing realisations is that our brains are shrinking. In 30,000 years, they have decreased from 1,500cm3 to 1,350cm3 – to roughly the size of a tennis ball. But is that a case of us becoming dumber, or are our brains becoming more efficient?
In years to come it may be hard to tell, as tiny machines become literally a part of who we are. Nanotechnology could manipulate molecular and atomic structures, enabling us to analyse and repair ailments in the body and extend lifespans. This would also open the door to potential enhancements of the body and mind, raising many ethical questions.
But at least this would be man and machine working in harmony. Another theory is that as artificial intelligence develops, we will outsource all the tasks that make us the planet’s dominate species. By creating robots that may surpass our intellect (known as the Singularity) we may no longer continue to evolve because our technological overlords won’t allow it.
And then we really will have to develop quickly to outsmart the pesky robots.