Book ReviewFlorian Fisch
Mark S. Blumberg:
Freaks of Nature, and What They Tell us About Development and Evolution.
Paperback: 352 pages
Publisher: Oxford University Press (December 1, 2009)
Price: 19.99 EUR
Johnny Eck (1911-1991), often billed as “King of the Freaks”
The shape of an animal is not as predefined as some may think. The disfigured of today may be the ordinary of tomorrow.
We are all freaks, in one way or another. This may seem quite wrong to most of us, but in fact we have just learned to live with our condition. Although we have only two legs, we have developed into an individual that is able to walk, just as Faith the two-legged dog learned to do it. Johnny Eck, a US-American freak show performer in the 1930s, had no legs at all but acquired the skill to elegantly move around on his arms.
In Freaks of Nature, Mark Blumberg uses a panoply of anomalies to show the importance of development in evolution. Many are not the result of mutations, but abnormal development due to environmental conditions during embryogenesis. Two-headed ducks are relatively common, probably because of some inappropriate movement of the egg in mother duck’s uterus. Blumberg enthuses the reader about development and argues convincingly that freaks can teach us a lot about its mechanisms.
Development is a constraint for evolution. New organs are rarely invented but old ones are reorganised. A snake is simply an elongated, slithering ribcage. There is a continuum from conjoined twins, sharing a placenta but having different amniotic sacs, to identical monozygotic twins having different placentas.
Also the variety of hermaphrodites is astonishing. Tobaccofish are normally simultaneous hermaphrodites, whereas many tropical fish are sequential hermaphrodites. The female of the spotted hyena could be mistaken for a hermaphrodite because her elongated clitoris looks very much like a male’s penis.
Despite the delicacy of the subject, Blumberg writes in a very respectful tone of all the individuals that others would call freaks, monsters or worse. Intentionally, he mentions the eugenics programmes of the 1930s and the ways of operating on intersexual babies today. He condemns the attitudes but not the people behind them. They often didn’t know better. Blumberg is on a mission to fight misconceptions of evolution. For him, freaks make it difficult to look for an intelligent designer. But at the same time he fights the “simplistic single-cause, gene-centered thinking that is so prominent today”. He sees evolution not as incremental, as the purely genetic “modern synthesis” of evolution would suggest, but as a process that proceeds in a discontinuous manner. Blumberg also defines epigenetics as the inheritance of any character (be it behaviour or the horn of certain beetles) that is not defined by genes directly.
His mission sometimes goes over the top. He is certainly right when he says that, “evolution [...] simply cannot produce creatures that development does not allow”. He also says that big beetle fathers get big beetle offspring because they help the beetle mothers to collect more food. Size, he says, as “an evolutionary important character can be inherited by the next generation without the mediation of a genetic mechanism”. This surely ignores the fact that even the development of large offspring from abundant food has a genetic basis, although certainly not based on a single mutation of a single gene.
We may forgive Blumberg, as he is a developmental behavioural neuroscientist and not an evolutionary biologist. Aside from that, his book is highly entertaining, easy to read and well structured. Frequent examples and clear illustrations help to get a good understanding of how the abnormalities explain the normalities of development. The book encourages us to admire the diversity of our world, rather than trying to eliminate nature’s blunders. “We no longer stare at them with horror. Our shock is replaced by awe. And, perhaps more importantly, by a sense of kinship”.
Letzte Änderungen: 29.07.2013