Evidence that two main bottleneck events shaped modern human genetic diversity — Proceedings B
Evidence that two main bottleneck events shaped modern human genetic diversity — Proceedings B
There is a strong consensus that modern humans originated in Africa and moved out to colonize the world approximately 50 000 years ago. During the process of expansion, variability was lost, creating a linear gradient of decreasing diversity with increasing distance from Africa. However, the exact way in which this loss occurred remains somewhat unclear: did it involve one, a few or a continuous series of population bottlenecks? We addressed this by analysing a large published dataset of 783 microsatellite loci genotyped in 53 worldwide populations, using the program ‘Bottleneck’. Immediately following a sharp population decline, rare alleles are lost faster than heterozygosity, creating a transient excess of heterozygosity relative to allele number, a feature that is used by Bottleneck to infer historical events. We find evidence of two primary events, one ‘out of Africa’ and one placed around the Bering Strait, where an ancient land bridge allowed passage into the Americas. These findings agree well with the regions of the world where the largest founder events might have been expected, but contrast with the apparently smooth gradient of variability that is revealed when current heterozygosity is plotted against distance from Africa.
The Phantom of Heilbronn and DNA testing.
Oops:
Police in Germany have admitted that a woman they have been hunting for more than 15 years may never have existed. Dubbed the "phantom of Heilbronn", the woman was dubbed by police as the country's most dangerous woman. Investigators had connected her to six murders and an unsolved death based on DNA traces found at the scene.
England’s rock art
The Northumberland and Durham Rock Art Pilot project has released a new website cataloguing England's Neolithic and Early Bronze Age Rock art. There's some truly beautiful pieces shown there - this is my favorite:
The Daily Mail also has an article on this project.
The Migration History of Humans: DNA Study Traces Human Origins Across the Continents
Scientific American covers the human diaspora in a nice broad-brush overview:
Fifty or sixty thousand years ago a small band of Africans—a few hundred or even several thousand—crossed the strait in tiny boats, never to return.
The reason they left their homeland in eastern Africa is not completely understood. Perhaps the climate changed, or once abundant shellfish stocks vanished. But some things are fairly certain. Those first trekkers out of Africa brought with them the physical and behavioral traits—the large brains and the capacity for language—that characterize fully modern humans. From their bivouac on the Asian continent in what is now Yemen, they set out on a decamillennial journey that spanned continents and land bridges and reached all the way to Tierra del Fuego, at the bottom of South America.
The Singing Cavemen
....and the award for the stupidest science story I've seen in months goes to LiveScience.com for "Cave Men Loved to Sing", in which we're told that our cave-dwelling ancestors used echo-location:
With only dull light available from a torch, which couldn't be carried into very narrow passages, the ancient hunters had to use their voices like sonar to explore the crooks and crannies of a newfound cave, Reznikoff explained.
"When acting in a cave in conditions similar to prehistoric ones ... the surroundings a few meters ahead are almost completely dark," he said, adding that "since sound reaches much farther than reduced light, especially in irregular surroundings, the only possibility and security is to explore the cave with the voice and its echoing effects."
This work is good, because... "(some work was done in past years and combined with the latest findings)". A scientific paper being based off previous findings... Fancy that.
The conclusions? -
Because Paleolithic humans had a deep connection with the melodic properties that helped them navigate in a cave, they likely celebrated the unique acoustics by singing in conjunction with their painting sessions.
European traditions: Phallus fights, cheese rolling, etc
Hanging from the neck of a live goose. Chasing a speeding wheel of cheese down a mountainside. Children smoking. Europeans do all of this and more.... Everyone knows about that annual tempting of fate known as running with the bulls in Pamplona. It's one of those festivals that make the saner among us scratch our heads in confusion and wonder, "How was that ever a good idea?"
