Are we humans simply remodelled apes? Chimps with a tweak? Is the difference between our genomes so minuscule it justifies the argument that our cognition and behaviour must also differ from chimps by barely a whisker? If “chimps are us” should we grant them human rights? Or is this one of the biggest fallacies in the study of evolution? NOT A CHIMP argues that these similarities have been grossly over-exaggerated - we should keep chimps at arm’s length. Are humans cognitively unique after all?
Friday, 7 August 2009
Orang-utans Use Tools To Deceptively Communicate
Here a group of primatologists, including Carel Van Schaik, report that orang-utans use strips of leaves, placed over their mouths, to modulate the kiss squeaks they emit when in distress. The leaves drive down the frequency of the kiss squeak to give the impression that the sound is being made by a larger animal than is the case. If all this stands up to further scrutiny it will be first evidence of tool use linked to a form of communication in which deliberate deception is involved.
More Clever Corvid Stuff
Nice BBC piece which reports on work that builds on earlier amazing findings relating to corvid tool use. In the first piece of research, Nathan Emery and Christopher Bird have found that Aesop's fable about a crow enjoying a "Eureka" moment by displacing water by throwing pebbles into a jar until the water surface rose to the point that it could drink, may well be grounded in fact. Their rooks have shown that they can plop pebbles into a cylinder containing a floating worm - up to the point where they can reach the worm with their beaks. Two rooks did it spontaneously when first presented with the task, the other two on their second attempt. They used larger pebbles when given variety thereby raising the water level more efficiently and they avoided worms on sand in favour of worms floating on water.
In a separate paper, Alex Kacelnik's group in Oxford report repeating the famous experiment conducted with Betty, just before she died, where the New Caledonian crow used a short tool to retrieve a medium-length tool to retrieve a long tool to pull out food from deep inside a horizontal tube. Four out of seven birds were spontaneously able to use the tools in the correct order, repeating Betty's swansong. As I explain in the book, this is an exceptionally important finding because, had the crows been learning by simple trial and error they would have found it impossible because the reward only comes after successfully negotiating three stages of tool selection. As Kacelnik is reported saying, "We are aware that the animals probably do it by putting together, in creative ways, things that they have learned individually". This is meta-tool use - using a tool to make a tool to use a tool.....and so on, to gain a reward. This is very sophisticated, human-like, cognition.
In a separate paper, Alex Kacelnik's group in Oxford report repeating the famous experiment conducted with Betty, just before she died, where the New Caledonian crow used a short tool to retrieve a medium-length tool to retrieve a long tool to pull out food from deep inside a horizontal tube. Four out of seven birds were spontaneously able to use the tools in the correct order, repeating Betty's swansong. As I explain in the book, this is an exceptionally important finding because, had the crows been learning by simple trial and error they would have found it impossible because the reward only comes after successfully negotiating three stages of tool selection. As Kacelnik is reported saying, "We are aware that the animals probably do it by putting together, in creative ways, things that they have learned individually". This is meta-tool use - using a tool to make a tool to use a tool.....and so on, to gain a reward. This is very sophisticated, human-like, cognition.
Jumping Genes Add Diversity To Human Brain
Fred Gage's lab at the Salk Institute have just reported finding that human brain cells are hyper-variable because their DNA harbours variable numbers of small DNA elements called LINE-1 elements (formerly referred to as junk DNA) which copy and paste themselves in great numbers throughout the genome. In this way, brain cells resemble immune system cells which are also hyper-variable because they have to constantly counter the barrage of different antigens that bombard our bodies. They discovered that LINE-1 jumping occurred much more frequently in brain tissue than in tissue from heart and liver and that the LINE-1 promotor, the switch that turns LINE-1 elements on and off, is permanently switched to "on" in the human brain. In this sense, LINE-1 insertion follows a pattern of several other means of gene regulation where the brain differs markedly from other body organs, in keeping with its need to remain flexible in response to rapidly changing environmental conditions throughout life. What Gage's team have not yet looked at is whether LINE-1 insertion and self-copying is extremely different between chimps and humans. My guess, obviously, is that it will be.
Wednesday, 5 August 2009
Brain Difference In Psychopaths Identified.
In the chapter on neuroscience (Inside The Brain) in NOT A CHIMP I describe in detail what scientists have dubbed "the social brain" - a number of heavily interlinked brain regions that receive inputs of relevant emotional stimuli from the outside world (for instance the amygdalae receive images of fear and pain) and process them into appropriate pro-social behaviour like true empathy and the ability to plan and behave appropriately among other human beings. Besides the amygdala, other areas include the orbitofrontal cortex, the insula and the anterior cingulate cortex. People who have damage to their orbitofrontal cortices become withdrawn and anti-social and behave inappropriately. Now a team of neuroscientists from Kings College, London have discovered that in the brains of psychopaths the white matter tract that connects the amygdala with the orbitofrontal cortex - the uncinate fasciculus - has structural abnormalities when compared to the brains of normal individuals. The degree of abnormality in the UF was directly related to the degree of psychopathy. Real pathology of the social brain.
Tuesday, 4 August 2009
Did Malaria Jump To Humans From Chimpanzees?
This CNN piece is one of several posts today documenting the recent discovery of the genetic similarity between Plasmodium reichenowi - the form of Plasmodium (the malaria parasite) common to chimps - and Plasmodium falciparum, the form common to humans and the cause of over 1 million deaths a year. It appears to be a complete vindication of the scientific argument of Ajit Varki, reported in chapter 5 of NOT A CHIMP - called "Less Is More". Nathan Wolfe has isolated and sequenced DNA from both malaria parasites and suggests, as did Varki before him, that falciparum evolved from the common chimp parasite, reichenowi, and spread, via mosquito vector, from chimps to humans. In fact, Varki's take on this event, which could have happened at any time between 10s of 1000's of years ago to 2 or 3 million, is more interesting because it suggests that, back in Homo erectus days, reichenowi was THE common malaria parasite to humans and chimps and that humans underwent drastic evolution to their immune systems in order to counter it. For some reason, reichenowi appears to be relatively harmless to chimps today and it may have been forever thus - so chimps never did evolve resistance to it. Eventually, Plasmodium countered human resistance by evolving the falciparum form from reichenowi, though whether or not chimps were the seat of this parasite evolution - and why - remains to be seen.
If you want to read up on this in more detail the source paper is Open Access in PNAS. The URL is http://www.pnas.org/content/early/2009/07/31/0907740106.full.pdf+html The authors specifically echo Varki's argument that humans inactivated the CMAH gene in a classic "less is more" mutation to prevent the sialic acid precursor Neu5Ac making Neu5Gc - which coats chimpanzee cells. A mutation converting P. reichenowi to P. falciparum then allowed it to target the now over-abundant Neu5Ac on human cells - accounting for its extreme pathogenicity in humans today.
If you want to read up on this in more detail the source paper is Open Access in PNAS. The URL is http://www.pnas.org/content/early/2009/07/31/0907740106.full.pdf+html The authors specifically echo Varki's argument that humans inactivated the CMAH gene in a classic "less is more" mutation to prevent the sialic acid precursor Neu5Ac making Neu5Gc - which coats chimpanzee cells. A mutation converting P. reichenowi to P. falciparum then allowed it to target the now over-abundant Neu5Ac on human cells - accounting for its extreme pathogenicity in humans today.
Orangutans Our Nearest Kin?
All the world loves a heretic, it seems. This clear piece by David Templeton, in the Pittsburgh Post-Gazette, outlines local boy Jeffrey Schwartz's continuing insistence that orangutans are more closely related to us than chimps. His argument is not based at all on genome comparisons, and particularly those calculations, based on genome divergence, that construct family trees of related species by drawing in divergence points from common ancestors (the forks in the tree). He relies on a host of morphological comparisons of which 28 are shared between human and orangutan versus 2 with chimps and 11 with gorillas. These include enamel molars, similar hairlines and shoulder blades and aspects of skull structure. His theory continues to draw scorn from over 99% of the evolutionary anthropology community and Todd Disotell, of the New York University Center for the Study of Human Origins, is preparing a point-by-point rebuttal of Schwartz's argument. Watch this space!