blueollie

Science: human endurance, basic particles and mimicry

Human endurance: this New York Times story talks about an incredible endurance athlete. The whole story is good; here is one bit:

Born into a Catalan family, Jornet grew up in the Spanish Pyrenees at 6,500 feet, and his gifts are literally in his blood. “When you are born and bred at altitude, you tend to have a higher blood volume and red-cell count for oxygen-carrying capacity,” which translates to better endurance, says Stacy Sims, a researcher at Stanford who holds a doctorate in exercise physiology and nutrition science. Years of daily running and skiing up mountains have further bolstered this advantage. This helps explain why Jornet sweats so little. During exercise, the bodies of very fit people quickly act to disperse heat by, among other things, vasodilation — expanding blood vessels at the skin’s surface where the air can cool the body. A body that sweats less loses less precious liquid from its circulatory system, a major factor in fatigue. In moderate temperatures, Jornet says, he can run easily for eight hours without drinking water.

For me: running at a moderate pace, I usually don’t drink during runs 2 hours or less. Walking: it is about 3 hours. No, I am not that fit and I do need to drink more when I am going very hard.

Physics Mano Singham has an interesting piece on particle physics. It requires a bit of effort to read, but it isn’t technical (though you have to know that subatomic particles are made of quarks and realize that mass of these particles isn’t just the mass of the quarks that make up the particle; the energy adds to the mass.

Human evolution
When we try to date human genetic lineages, the mutation rates are important:

Recent measurements of the rate at which children show DNA changes not seen in their parents — the “mutation rate” — have challenged views about major dates in human evolution.

[...]

The researchers show that pre-ice age hunter-gatherers from Europe carry mtDNA that is related to that seen in post-ice age modern humans such as the Oberkassel fossils. This suggests that there was population continuity throughout the last major glaciation event in Europe around 20,000 years ago. Two of the Dolni Vestonice hunter-gatherers also carry identical mtDNAs, suggesting a close maternal relationship among these individuals who were buried together.
The researchers also used the radiocarbon age of the fossils to estimate human mutation rates over tens of thousands of year back in time. This was done by calculating the number of mutations in modern groups that are absent in the ancient groups, since they had not yet existed in the ancient population. The mutation rate was estimated by counting the number of mutations accumulated along descendent lineages since the radiocarbon dated fossils.
Using those novel mutation rates — capitalizing on information from ancient DNA — the authors cal-culate the last common ancestor for human mitochondrial lineages to around 160,000 years ago. In other words, all present-day humans have as one of their ancestors a single woman who lived around that time.

There is more there; right now there is a disparity between modern family mutation rates and the observed mutation rates of ancient humans (as derived from fossils.

Biological Mimicry
Both the hunters and the prey benefit from camouflage. There is a gecko that resembles a leaf; below is an insect that also resembles a leaf.

leafgekko

leafyinsect

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March 23, 2013 - Posted by | evolution, nature, physics, science, ultra | , , ,

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