It's often said that humans have stopped evolving,
but is this true?
The fact is, we're still evolving today.
Well, sort of
and we'll continue to do so into the future.
It's built into the basic fabric of our biology.
Evolution will continue because of the way our DNA copies itself
and mixes itself up when sperm and eggs are made.
Between generations, genes shuffle about at random
making each generation genetically unique.
Charles Darwin's idea of natural selection is based on the fact that most organisms, including people,
show physical and genetic variation.
Change the environment just a little bit, and some individuals will be better adapted because of their DNA.
They'll have more offspring who'll survive to pass on their DNA to future generations.
Currently, we're changing the environment a lot.
Global warming
rising pollution levels
the overuse of antibiotics
pesticide resistance in insects
a lifestyle based on little physical activity and focused on technology
and even delaying having children until our thirties or forties.
Any one of these might lead to pressures that accelerate evolution in humans.
Changes could be in the genes for our immune system
our sweat glands
the number of disease causing genes carried in sperm cells
even others affecting our skeleton, muscles and nervous system.
Sound far fetched?
Well actually, we have a pretty good case study from recent evolution.
The invention of agriculture around ten thousand years ago led to dramatic shifts in our genes.
For those of us with farming ancestors, scientists reckon that more than 70% of our genetic variation
and about 90% of diseased genes, arose in the last five to ten thousand years.
That's a staggering amount of genetic evolution in a very short time.
And this was all the result of a remarkable shift in lifestyle.
The end of hunting and gathering and the beginning of agriculture.
We went from just a few million people worldwide ten thousand years ago
to around seven billion people today, all crowded on a tiny planet.
Some geneticists even think the amazing number of rare gene mutations built up over the last five thousand years
could trigger a whole new species of human to evolve.
But could we see large, physically obvious changes in the future?
Like those we see between species?
It's even predicted that we humans will shape our own evolutionary destinies in the future
engineering our bodies through genetic technology to live for hundreds of years
or to be perfectly built for a life in space.
The challenge for us all is to make sure no person or population gets left behind
because they don't have the cash to enjoy the benefits of genetic engineering or new medical technologies.
Evolution will continue but unlike any time in the past, we now understand its causes
and can deal with the consequences for the benefit of all humankind.