Thursday, February 19, 2009
Boskone 2009 Evolution Panel
I was also part of the Evolution Panel at Boskone. Here are my notes from that.
Human acceptance of evolution
• >1/2 Americans don't believe humans descended from earlier animals. Similarfor Brits.
• Alfred Wallace didn't think natural selection applied to human beings.
• We know about the different school systems: Dover, Texas, Arkansas, Kansas.
• Where physics happens outside of us; biology (evolution) happens inside of us. It says where we came from.
• The implied limitation of God.
• The comfort of evolution: We know where we came from and where we're going.
• Evolution is not human centric. Progression of scientific thought is away from human centric.
• Nature of religion is steadiness and constancy. Nature of science is change. Natural selection is not in jeopardy. But our understanding how it is implemented is. Even the concept of species is insecure.
• Humans are uncomfortable with insecurity. No one likes to say I Don't Know.
• There are creationist investigators-- you can't really call them scientists-- that are trying to recast physics in some way that the Young Earth Creationism is viable.
• Not entirely clear on how people can deny something that is so obvious. Gee: electricity makes lights. The sky is blue. Evolution is obvious.
Seems like there are subgroups of human evolution:
Survival selection: Adaptations that favor physical survivorship of individuals
Reproductive selection: Adaptations that favor reproductive success
Sexual selection: Female choice of mates.
Cultural selection. The ability to navigate cultural complexities in order to achieve reproductive success.
Neat recent things about evolution
• FOXP2 work show its use in language, bird songs and echolocation. Humans have 2 mutations that chimps don't. What does that mean? No one knows.
• MYH16 function is lost. In chimps it is active only in the muscles of the head, including chewing muscles. Relaxation of these muscles result in skull growth freedom?
• Brain size is controlled by at least 4 genes. Knocking out some of these genes results in microcephaly. These genes are evolving more rapidly in primates than rodents and especially fast in chimps and humans.
• 4 mutations are involved with different forms of lactase preservation. European lactose tolerance comes from one mutation. African from others. Euro form is about 7,000 years old. Africa about 5,000.
• Gene duplication appears highly correlated with human evolution. Salivary amylase is one.
• Pace of evolution is speeding up in the last 40,000. In the last 5-10k, evolution has speeded up to about 100 fold as measured by gene adaptation over time.
• DRD4, a version of a dopamine receptor gene, is sweeping through the Euro population right now.
• Blue eyes appeared between 6 and 10k years ago and has appears to have a 5% evolutionary advantage. Why? no one knows. Darwin thought it was sexual selection. Some other scientists think its associated with an actual advantage that is unknown.
• Neanderthals have been sequenced. Doesn't look like we interbred. But they also have the FOXP2 gene.
• Tiktaalik discovery based on evolutionary predictions: a time lapse set of fossils show the evolution of tetrapoda from fish.
• Platypus sequence: sex chromosomes that sequence like birds but act like mammals.
• Lancelet genome is helping sort out chordate evolution. Have most of the same genes as vertebrates and they are arranged similarly in the chromosomes.
• Trichoplax has something that acts as nerves but has no nerve tissue. However, it has many of the genes necessary to transmit nerve impulses indicating an underlying structure to support nerves prior to when they exist. Darwinian evolution: The structure selected upon predates the selection.
• Evo-Devo: The path of evolution through developmental embryology. Gene regulation of other genes.
• Soft inheritance: ancestral environmental experiences cause later generational effects. Epigenitic generational inheritance. So far the process best understood is by DNA methylation. Stress conditions can cause it. Disease can show up. Variations in flower morphology. Etc.
• Oldest eucaryotic life may be sponges.
Speciation and the Web (not Tree) of Life
Horizontal gene transfer:
• "The battle came to a head in 2006. In an ambitious study, a team led by Peer Bork of the European Molecular Biology Laboratory in Heidelberg, Germany, examined 191 sequenced genomes from all three domains of life - bacteria, archaea and eukaryotes (complex organisms with their genetic material packaged in a nucleus) - and identified 31 genes that all the species possessed and which showed no signs of ever having been horizontally transferred. They then generated a tree by comparing the sequences of these "core" genes in everything from E. coli to elephants. The result was the closest thing yet to the perfect tree, Bork claimed (Science, vol 311, p 1283).
• Other researchers begged to differ. Among them were Tal Dagan and William Martin at the Heinrich Heine University in Düsseldorf, Germany, who pointed out that in numerical terms a core of 31 genes is almost insignificant, representing just 1 per cent of a typical bacterial genome and more like 0.1 per cent of an animal's. That hardly constitutes a mighty oak or even a feeble sapling - more like a tiny twig completely buried by a giant web. Dagan dubbed Bork's result "the tree of 1 per cent" and argued that the study inadvertently provided some of the best evidence yet that the tree-of-life concept was redundant (Genome Biology, vol 7, p 118).
• Last year, for example, a team at the University of Texas at Arlington found a peculiar chunk of DNA in the genomes of eight animals - the mouse, rat, bushbaby, little brown bat, tenrec, opossum, anole lizard and African clawed frog - but not in 25 others, including humans, elephants, chickens and fish.
• HGT has been documented in insects, fish and plants, and a few years ago a piece of snake DNA was found in cows. The most likely agents of this genetic shuffling are viruses, which constantly cut and paste DNA from one genome into another, often across great taxonomic distances.
• based on reproductive isolation as set out by Ernst Mayr in 1942.
• But Darwin, who once wrote that species were “indefinable”, might have described a species as a segment of a branch on the ever-expanding tree of life, the same tree he drew as the only figure in the “Origin.” Or he might have said it was something more distinct than a variety and less than a genus.
• Genetic reproduction isolation genes, Nup 160 and Nup 96, in fruit flies. Seems to be involved in the nuclear pore complex that controls what molecules enter or leave the nucleus. What does this have to do with hybrid sterility? Another class of genes in plants, involved in fending off disease, may be involved in speciation in plants. Speciation genes appear to have diverged under powerful natural selection.
• Sexual selection is now showing itself in action: A small Amazonian frog known as Physalaemus petersi provides a particularly strong example of how females’ choosiness in mates may be driving the formation of a new species. Males of the mottled brown species reach just over an inch in length and can be found singing in choruses to attract females. In some populations, the males’ song is what is called a “whine” — a kind of frog meow. But in other populations, males whine and add a squawk. Michael J. Ryan, an evolutionary biologist at the University of Texas, Austin, and colleagues have found that the difference evolved because females in one population preferred pure whine, whereas in another they preferred whine and squawk.
Links of Interest
The Skylon Spaceplane
Fuel Boost from Bumps
Wooden Gear Window Blinds
Pride and Predator
NYC Toy Fair: Here. Here. Here. Here. Here. Here. Here. Here. Here.
Quantum Weirdness Day
Home CO2 Scrubber