TV Review- What Darwin Didn't Know.
So the beeb is going all out with the marking of Darwin's 200th birthday and the 150th anniversary of the publication of "On the Origin of Species". As part of this they have several TV programmes. Including "What Darwin Didn't Know" a 90 minute documentary by the biologist Armand Leroi, discussing the various problems that Darwin foresaw in his theory, and how these gaps have been filled.
(This programme should not be confused with Geoffrey Simmons book of the same title about ID, by a guy who thinks whales are evidence against evolution, but knows nothing about their fossil record).
It deals with the fact that Darwin didn't have a workable theory of inheritance, plumping for a blending hypothesis, which clearly has problems- novel traits will be quickly diluted, so can never spread. One thing it covers in a good degree of detail is the "Eclipse of Darwinism" that happenned soon after his death. Scientists discovered mutations, and came up with ideas about "orthogenesis" species passing along defined evolutionary paths, like those of a developing embryo. Natural selection was pretty much ignored. Even when Mendelian genetics was rediscovered it took until the 1920s and 30s to really get to grips with what was going on. Leroi largely skips over this, concentration on one of the competing theories (Hugo de Vries' model that suggested that all evolution needed was mutations to occur). If he'd have gone into any more detail he;'d probably have filled the entire programme, which is a pity, because the rest of the show was also extremely good.
One of the most interesting fields to have developed since Darwin is that of "evo-devo", the examination of shared genetic and developmental pathways across groups. For instance the gene Pax-6 is responsible for initiating eye development in both humans and insects. Alter it in a fruit fly and you get an eyeless fly (which is what it sounds like). In humans the same kinds of mutations exist, and the condition aniridia results- children are born without an iris, and thus have trouble seeing.
Similarly a characteristic shared across animals is the presence of a particular group of genes called Hox genes. These control development, and like Pax-6 operate as switches turning other genes on and off in different parts of the genome. When these genes are expressed incorrectly we can see what they do. We have, it seems come full circle and are back to de Vries' cataloguing and examination of mutants, albeit using techniques that he and Darwin would be astounded by.
Its available on BBC iPlayer (for the UK residents) until the 4th of February, but I'm sure its crept onto the filesharing websites by now.
(This programme should not be confused with Geoffrey Simmons book of the same title about ID, by a guy who thinks whales are evidence against evolution, but knows nothing about their fossil record).
It deals with the fact that Darwin didn't have a workable theory of inheritance, plumping for a blending hypothesis, which clearly has problems- novel traits will be quickly diluted, so can never spread. One thing it covers in a good degree of detail is the "Eclipse of Darwinism" that happenned soon after his death. Scientists discovered mutations, and came up with ideas about "orthogenesis" species passing along defined evolutionary paths, like those of a developing embryo. Natural selection was pretty much ignored. Even when Mendelian genetics was rediscovered it took until the 1920s and 30s to really get to grips with what was going on. Leroi largely skips over this, concentration on one of the competing theories (Hugo de Vries' model that suggested that all evolution needed was mutations to occur). If he'd have gone into any more detail he;'d probably have filled the entire programme, which is a pity, because the rest of the show was also extremely good.
One of the most interesting fields to have developed since Darwin is that of "evo-devo", the examination of shared genetic and developmental pathways across groups. For instance the gene Pax-6 is responsible for initiating eye development in both humans and insects. Alter it in a fruit fly and you get an eyeless fly (which is what it sounds like). In humans the same kinds of mutations exist, and the condition aniridia results- children are born without an iris, and thus have trouble seeing.
Similarly a characteristic shared across animals is the presence of a particular group of genes called Hox genes. These control development, and like Pax-6 operate as switches turning other genes on and off in different parts of the genome. When these genes are expressed incorrectly we can see what they do. We have, it seems come full circle and are back to de Vries' cataloguing and examination of mutants, albeit using techniques that he and Darwin would be astounded by.
Its available on BBC iPlayer (for the UK residents) until the 4th of February, but I'm sure its crept onto the filesharing websites by now.