Australasian Science Magazine

By Michael Cook

Since IVF bypasses infertility it must also be having an effect on human evolution.

Evolution works because of differential reproduction. If an organism has a harmful gene, it will perish before reproducing or fail to have offspring. Infertility may be nature’s way of decreeing that this man or this woman, or this couple, are not “fit” in the evolutionary sense.

So surely IVF, which enables people to bypass their infertility, must be having an effect upon human evolution.

This question was tackled by Norwegian scientists recently in the leading journal Human Reproduction. They wrote: “Assisted reproduction is redefining human society and biology and, in the face of profound ethical issues, it is important to understand the technical and conceptual principles that underlie this new paradigm”.

They point out that IVF systematically changes selection pressures, involving “a combination of artificial environments and selection criteria that are distinctively different from those of natural reproduction”.

They give examples. IVF eggs can survive harsh laboratory conditions, including puncturing it to insert a sperm. IVF also favours sperm that swim fast for a short distance while nature “favours long-distance swimmers that are able to navigate the female reproductive tract”.

IVF embryos survive contact with plastic surfaces, exposure to light, mechanical manipulation, living in a Petri dish and abrupt temperature changes. There may be differences in how IVF embryos survive implantation and miscarriage.

Even the couples are different, as “the limited availability of IVF favours healthy sub-fertile couples in stable relationships who live in high-income societies”.

The authors stress that much of what they say is speculative, but they conclude: “The most extreme evolutionary scenario is a subpopulation in which reproduction is entirely dependent on IVF … Overall, it seems clear that IVF facilitates the propagation of genetically heritable traits of sub-fertile couples, and we suspect that ongoing studies of IVF offspring will show an increased risk of subfertility for this group.”

Apart from allowing infertile people to reproduce, IVF may select for traits such as resistance to exposure to plastic surfaces. What the results of this will be is completely unknown.

Other recent papers in the same journal point out that the Petri dishes in which IVF embryos spend the first days of their lives affect the birthweight of the resulting babies – and possibly their long-term health.

In a blistering editorial, Hans Evers, the journal’s editor, admitted that he knows far more about the ingredients in his favourite peanut butter than he does about embryo culture media. “It’s not possible to sell a single drug on the market if you do not give the total composition of the drug, but for such an important thing as culture media, that envelopes the whole embryo, you can sell it without revealing its contents,” Evers told New Scientist. “Compared to the rest of medicine, this is such a backward area. We can’t accept it any longer.”

A working group of the European Society of Human Reproduction and Embryology, led by Prof Arne Sunde of The University Hospital in Trondheim, Norway, has found that culture media for IVF embryos vary widely, their composition is usually unknown by the end users, and data about the influence of the media on embryos are conflicting.

“We have no information about long-term consequences of this, but we cannot rule out that the composition of the culture media may affect the health of children as they grow up and become adults,” Sunde says.

One possibility, according to the Barker Hypothesis is an epidemic of chronic disease.

The Barker Hypothesis stems from the health of Dutch children conceived during a severe famine in German-occupied part of The Netherlands during the winter of 1944–45. It was a perfect experiment on the effect of gestation on adult health. In middle age these children of starving mothers are suffering from obesity, dementia, hypertension, coronary heart disease and diabetes. The results may very well be relevant to the harsh and unusual environment of the Petri dish.

The worst-case scenario is that while an IVF baby may be a delight to cuddle, 50 years later an IVF adult could be an overweight, doddering, diabetic, stroke-prone candidate for a heart attack. The millions of IVF children now alive may be health time-bombs.

We don’t know. The first IVF baby, Louise Brown, is only 38.

Back to the Norwegian scientists’ musings about IVF and evolution. Let them have the last word. They conclude, somewhat ominously, that IVF is making reproduction increasingly dependent upon artificial means: “It is our opinion that IVF should be seen as a primary example of how the human species is becoming not only culturally – but also biologically – dependent on our own technology”.