Related article: anatomical evolution. In a remarkable contribution at the conference,
Katerina Harvati and Himalaya Gasex Tablets Tim Weaver of the Max Planck Institute for
Evolutionary Anthropology in Leipzig, Germany, looked at skull
variation in modern humans from different climates and cultures. They
found that the shape of the face is linked to local environmental
conditions, which fits well with the current belief that the
Neandertal's projecting face is a cold-climate adaptation. By
contrast, the shape of the brain case, Buy Cheap Gasex particularly the temporal bone
(on the side of the skull), proved to be a good indicator of genetic
closeness among populations.
Real Molecules
Meanwhile, the genuine specimens have been the object of increased
attention through the study of DNA, proteins, and chemical elements
that can be found in bones and teeth--giving us a completely new
source of valuable information about our remote relatives' biology and
their daily lives.
In 1997, a fragment of DNA was reconstructed from the same bones that
the quarry workers found in Neandertal in 1856. The DNA Buy Gasex of the
Neandertal fell outside modern human variation, and Himalaya Gasex suggested a
divergence between the ancestors of Neandertals and modern humans
nearly half a million years ago. Since the original DNA study, nine
other Neandertal individuals have yielded some genetic information,
all similar to one another yet distinct from that of modern humans.
Although this number is small, the evidence gives us insight into the
demography of the Neandertals. Order Gasex Online The limited variability of their DNA
suggests that there were times, perhaps during glacial advances, when
their population was greatly reduced, resulting in genetic
bottlenecking. The population recovered in size afterward but with
fewer surviving different genetic lines. In this respect,
humans--modern, Neandertal, and others--strongly contrast with African
apes, which evolved in a much Purchase Gasex Online less stressful environment during the
last several hundred thousand years, and therefore have much greater
genetic variability.
Interestingly, while we can now study Neandertal DNA, it is very
difficult to analyze DNA from the early modern humans who replaced
them between 40,000 and 30,000 years ago. Because Neandertal DNA is
different from our own, modern contamination (from excavators, museum
curators, or laboratory personnel) can be identified and discounted.
With fossils of our own forebears, however, differentiating ancient
DNA from recent contamination is virtually impossible. Such research
can only be undertaken with new fossil finds that are kept in sterile
conditions from the field to the Buy Gasex Online lab.
There is no evidence that the last Neandertals were evolving toward a
physical appearance like our Order Gasex own, but the issue of the possible
contribution of Neandertals to the modern European genetic makeup is
still fervently debated. Even if Neandertals represented a distinct,
although very close, species separate from modern humans, we know that
in nature, hybridization Gasex Tablets is a common process under such circumstances.
At the conference, Trenton Holliday of Tulane University surveyed the
zoological evidence, pointing out many hybrids among large mammals
including members of the camel, horse, dog, and cat families. Did
Neandertals and modern humans interbreed? It is quite possible in some
instances, but it had no major biological results.
Proteins can now be recovered from bones and examined with methods
similar to those used with DNA. This Gasex Dosage year, for the first time,
Christina Nielsen-Marsh of the Max Planck Institute was Purchase Gasex able to
extract and analyze a protein from Neandertal teeth from Shanidar,
Iraq. In Neandertals, this particular protein (osteocalcin) displays a
sequence similar to that of modern humans, Gasex Himalaya indicating it has changed
little over a long period of time. In the near future, extraction and
sequencing of fossil proteins may open new ways to study evolutionary
relationships between extinct species, and may allow us to go farther
back in time than is possible with ancient DNA, which is more complex
and degrades more quickly.
Scientists are investigating other molecules and chemical elements
found in Neandertal bones. Collagen, routinely extracted from bone
today for radiocarbon dating, yields carbon and nitrogen, while
strontium and calcium can be sampled from the mineral parts of bone.