Life
Rethinking biology: Eva Jablonka
David Edmonds' Jewniversity column examines the contentious theories of a biologist who challenges Darwin
April 4, 2018 12:22
David Edmonds' Jewniversity column examines the contentious theories of a biologist who challenges Darwin
April 4, 2018 12:22In Britain, only religious fundamentalists reject the overwhelming evidence that animals have evolved over time and that humans and apes have common ancestry. In the United States, by contrast, it’s a less settled matter. Two in every five Americans endorse a biblical creationist version of the origin of life.
That may be one reason why scientists are acutely sensitive to any critique of evolutionary theory — and it goes some way to explain why the work of theoretical biologist Eva Jablonka has proved so contentious.
But first, some backstory. Darwin published On the Origin of Species in 1859. Pre-Darwin there had been an alternative evolutionary theory, proposed by the French biologist Jean-Baptiste Lamarck. Crudely put, Lamarck believed the following: suppose there was an environmental change and giraffes found it more difficult to locate food on the lower branches of trees — they would then be forced to stretch their necks to reach the higher branches. And, as a result, their future offspring would also have longer necks.
Darwin rejected this account. He thought that if giraffes with longer necks had an advantage over giraffes with shorter necks, then they would be more likely to stay alive and more likely to reproduce. Short-necked giraffes would die out— and that’s how giraffes would end up with longer necks. It was survival of the fittest.
Darwin knew nothing of genes, but the genetic revolution, which began in the late 19th Century, both supplemented and corroborated the Darwinian story. Now we understood that the transmission mechanism for passing on traits to our children was through our genes.
There was nothing we could do in our lifetime to alter our DNA, which we would pass on to our kids.
Enter Eva Jablonka. When she first began to question the old orthodoxy, biologists conspicuously walked out of her lectures. Along with a colleague, she had begun to gather data that seemed to suggest Lamarck wasn’t entirely mistaken after all. Her field of “epigenetics” involves the examination of heritable changes where there is no change in the DNA sequence.
The evidence comes mainly from plants and animals. In one experiment, in which young mice and their mother were put under stress (principally through separation), symptoms of stress were observed over three generations.
There is additional evidence — admittedly weaker — from humans. Most famously, detailed Dutch health records suggest that even the grandchildren of malnourished mothers, during the Hongerwinter, the Nazi-induced Dutch famine of 1944/5, have a variety of health issues, even though this generation was well fed. Some have argued that Holocaust survivors have passed on trauma to their children — not just by how they nurtured them, but biologically.
Research into how this may occur is ongoing. There may be various mechanisms — for example, epigenetics could involve a change in the chromosome which then changes whether or not a particular gene is expressed.
In any case, the possibility of epigenetics is no longer considered outlandish. And for this, Jablonka deserves much credit. She says she owes her interest in ideas to her family.
She was born in Poland in 1952. Her mother had survived the war in Warsaw with false papers. Her father escaped to Russia in 1939 where he was promptly arrested and dispatched to the Gulag, for several brutal years.
The family left Poland for Israel in 1957, with Eva’s father suspecting his antisemitic work colleagues were spreading lies about him.
He became a banker in Israel, while her mum worked in a school. Jablonka was raised in a secular-socialist-Zionist household, full of books and discussion and with an emphasis on education.
If Jablonka is right, then certain things that her parents did, or that happened to them, could in some way have been inherited by her.
This new epigenetic picture of inheritance has, of course, nothing in common with creationism. But it does add a radical twist to the previous orthodoxy.
And these days, when Eva Jablonka delivers a lecture, the audience stays to listen.
David Edmonds is the host of the BBC World Service’s The Big Idea. Next week the programme features Eva Jablonka. Transmission details are on the BBC’s website.
