Wednesday, September 16, 2009

Your Hippocampus Remembers More than You Do

Remembering Without Knowing It
In a memory task in which the subject was shown a photograph and then later asked to pick out that photo among several others, the subject's hippocampus activated when they were seeing the correct photo, even when they ended up choosing the wrong one!

Cosmology Review

Cosmology at a Crossroads
A fundamental question in cosmology is, "How did the universe begin?" The two pivotal ideas of inflation and cold dark matter (CDM), combined with extensive observational results, including the unpredicted accelerated expansion of the universe, underpin a new standard model of cosmology

Neanderthals were more Carnivorous than early modern Humans

Isotopic evidence for the diets of European Neanderthals and early modern humans
Neanderthals mainly fed on big-game, while early modern humans had a more varied diet, sometimes including lots of fish.

Genetics of the Human Expansion Out of Africa

Explaining worldwide patterns of human genetic variation using a coalescent-based serial founder model of migration outward from Africa
It seems that modern humans may have expanded out of Africa without mixing much with the descendants of earlier waves of migration.

Larvae and Adults are Hybrids??

Caterpillars evolved from onychophorans by hybridogenesis
I reject the Darwinian assumption that larvae and their adults evolved from a single common ancestor. Rather I posit that, in animals that metamorphose, the basic types of larvae originated as adults of different lineages, i.e., larvae were transferred when, through hybridization, their genomes were acquired by distantly related animals. “Caterpillars,” the name for eruciforms with thoracic and abdominal legs, are larvae of lepidopterans, hymenopterans, and mecopterans (scorpionflies). Grubs and maggots, including the larvae of beetles, bees, and flies, evolved from caterpillars by loss of legs. Caterpillar larval organs are dismantled and reconstructed in the pupal phase. Such indirect developmental patterns (metamorphoses) did not originate solely by accumulation of random mutations followed by natural selection; rather they are fully consistent with my concept of evolution by hybridogenesis. Members of the phylum Onychophora (velvet worms) are proposed as the evolutionary source of caterpillars and their grub or maggot descendants. I present a molecular biological research proposal to test my thesis. By my hypothesis 2 recognizable sets of genes are detectable in the genomes of all insects with caterpillar grub- or maggot-like larvae: (i) onychophoran genes that code for proteins determining larval morphology/physiology and (ii) sequentially expressed insect genes that code for adult proteins. The genomes of insects and other animals that, by contrast, entirely lack larvae comprise recognizable sets of genes from single animal common ancestors.

I would be surprised if this were true, but it's an interesting and novel hypothesis.

Sanction Threats reduce Reciprocity

Neural responses to sanction threats in two-party economic exchange
Sanctions are used ubiquitously to enforce obedience to social norms. However, recent field studies and laboratory experiments have demonstrated that cooperation is sometimes reduced when incentives meant to promote prosocial decisions are added to the environment. Although various explanations for this effect have been suggested, the neural foundations of the effect have not been fully explored. Using a modified trust game, we found that trustees reciprocate relatively less when facing sanction threats, and that the presence of sanctions significantly reduces trustee's brain activities involved in social reward valuation [in the ventromedial prefrontal cortex (VMPFC), lateral orbitofrontal cortex, and amygdala] while it simultaneously increases brain activities in the parietal cortex, which has been implicated in rational decision making. Moreover, we found that neural activity in a trustee's VMPFC area predicts her future level of cooperation under both sanction and no-sanction conditions, and that this predictive activity can be dynamically modulated by the presence of a sanction threat.

Jumping Robot

Video: Precision Urban Hopper leaps over fences, makes enemies cringe