Do species really exist? Are genes destiny? Do only the fittest survive? Can we shape or stop evolution? New insights into nature are providing surprising answers, and a glorious new picture of life’s complexity
23 September 2020
1 GENES AREN’T DESTINY
The principle of genetic plasticity
IN 1990, an international group of scientists embarked on one of the most ambitious research projects ever undertaken. They would sequence the entire human genome, determining the order of the 3.3 billion base pairs that code for the genes that make the proteins that each of us are built from. There was huge excitement at the prospect of decoding the “blueprint” of humanity. Given the complexity of our species, our genome was expected to contain at least 100,000 genes. What makes us human would finally be laid bare.
It didn’t quite work out like that. The Human Genome Project was a resounding success, publishing its results in 2003, two years ahead of target. However, it revealed that humans only have around 22,000 genes, which is about the same number as other mammals. Meanwhile, the blueprint itself turned out to be encrypted in ways we are still trying to crack.
The same thing is true of us that is true of every species: our DNA can be expressed in myriad different ways depending on which combination of sequences is activated. It is this, not the number of genes in the genome, that creates the complexity of life.
The more we learn about genetics, the clearer it becomes that “genetic determinism” – the idea that genes and genes alone fix our destiny – is a myth. A given set of genes has the potential to produce a variety of observable characteristics, known as phenotypes, depending on the environment. An Arctic fox changes its coat colour with the seasons. The …