Science - March 3, 2010

Bypassing Darwin

Human beings have become weaker genetically because natural selection has little hold on us. Genetician Rolf Hoekstra can demonstrate this convincingly. He doesn't have a cure, though, since it's inhuman to breed humans or to forbid them to have children.

With the Caesarian section, we deny ourselves the workings of natural selection for small children heads or big virginal openings.
Throughout his academic career, he has studied the evolution of bacteria and fungi. Not during the coffee breaks, though. Then, professor of genetics Rolf Hoekstra likes to talk about humans. In a very unconventional way, except when seen through the eyes of an evolution biologist. In his farewell lecture - two weeks ago - he listed some literature which confirms his hypothesis: human beings are denying ourselves the process of natural selection and that makes us genetically weaker.
For example, more children are born via the abdomen; in the U.S., this is one out of three births. A caesarean section is necessary, such as when the baby's head is bigger than the birth canal. This is an evolutionary inheritance: baby heads of chimpanzees fit nicely through the virginal opening, but our brains are bigger and the virginal opening has become smaller when human beings started to walk upright.
But with the caesarean section, the westerner has been denied the process of natural selection of, for example, small children heads or big virginal openings. This also applies in cases of infertility: IVF, artificial insemination and hormone treatments have enabled infertility to be passed down to the next generation. Procreation is no longer linked directly to biological processes.
Hoekstra gives another example. Medicine hinders us from developing resistance. It is probable that we were resistant in the past against diseases such as the plague; those who were not, died and therefore had less chances to pass on his plague-sensitive genes. But we will not be resistant against, for example, HIV. A small number of Europeans has this resistance. Without aids drugs, a large part of the population would have HIV-resistance in their genes a few thousand years from now. That's not going to happen, because people who have been infected would survive because of medication.
 
BREEDING HUMANS
Rolf Hoekstra points out the problem of failed selection, but doesn't have a solution for it. Well, there are ways, but he finds them inhuman. You can't go about selecting genetically weak people in order to deny them medical care or to thwart their wish to have children.
What about genetic enrichment? Breeding humans, or intervention in partner choice, is not an option, of course. At most, gene therapy or embryo selection can be the answer for mutations which can lead to heavy handicaps - like the pre-implantation genetic diagnosis in Maastricht, where women with hereditary cervical cancer can spare their daughters from such.
But that won't help humanity as mutations with a small adverse effect occur more often, as Hoekstra got to know from his own experiments with fungi and bacteria. Such small deviations are difficult to trace - sometimes this has to do with gene interaction - but they accumulate especially in a weak natural selection. In the long run, our offspring will have more medical problems and will require more and more care.
 
STERALIZATION
Western society feels that procreation is the responsibility of the individual and not of the country. This ethic can mainly be attributed to the nineteen thirties.. Eugenics has become taboo since the Nazi horrors and sterilization of the weak in the US and Scandinavia.
Hoekstra does, however, see that ethics can be flexible, and we could think differently two hundred years from now. He quotes the Greek thinker Plato, who felt that a country should be allowed to determine who should have children and who not. One example from modern times is China with her communist party which has for years maintained the one-child policy.
Even here, the individual is not completely free to do as he wishes. In the Netherlands, intellectually very disabled parents are given birth control injections. We believe that they shouldn't conceive any children. To protect the child, not the species.
Authority comes under pressure
 
This university as an authority is diminishing in importance because much research is now being paid for by the private sector or by policy makers. Rolf Hoekstra, professor in Wageningen from 1989 to 2010, points out that he has worked with much pleasure here, but parts with a word of caution. 'I see a trend where all sorts of little kingdoms are moving towards an organization tightly organized at the top. The university has become more like a company where profit-making is important. It isn't always pleasant this way.'
This private sector approach can undermine the university's authority, Hoekstra thinks. 'This is very clearly seen in the climate discussions. Society becomes suspicious of the learned, because 'so-and-so has connections with so-and-so'. But ties with the industry are highly stimulated and we are expected to bring in research projects from the private sector.'
In addition, the private sector approach also influences the research agenda. 'I had always been able to do what I wanted to, but research is increasingly being dictated by the graduate schools and the knowledge groups. The university wants to present itself as having a clear mission and strategic plan. Otherwise, society may consider stopping to invest money if it's told that some chair groups do as they like.'
'Pure inquisitive research has hardly any place here. Fortunately, people such as Martin Kropff recognize this, and someone has to. Otherwise, renewal would not be possible.
Successor
The appointment committee has nominated Bas Zwaan as successor to Hoekstra. Zwaan works currently as evolution biologist at the Leiden University, where he studies the evolution of aging and natural selection of body shapes in butterflies.
 

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