Darwin Finches’ Beaks and Songs
A new theory is being proposed that says that not only were the beaks of Darwin’s finches adapted in size and shape for the food eaten, but they also changed the songs of the birds. We see some examples of the finches in the LOT exhibit. These changed songs allowed the birds with the same beaks to recognize each other for mating. An article by Jeffrey Podos in Nature says that the different shapes themselves may cause some of the change (the bigger beaks have low rates of syllable repetition and narrow frequency bands compared to the smaller birds). This may indicate how the change in the shape of the beak would change the song and therefore aid in reproductive isolation and rapid speciation.
Modern Human Origins Debate Continues
A recent article in Nature presented more proof for the Out of Africa Theory that was shown by extensive DNA analysis of living humans. This study analyzed DNA from 53 humans of different ethnic and geographic locations. Africans showed the greatest amount of variation indicating that they were the origin of all humans. Using a molecular clock assumption they estimate that humans broke from chimps 5 MYA and that the common ancestor of modern humans lived 170,000 YA.
Now in the recent issue of Science, Milford Wolpoff et al strongly argues for the Multi-Regional Theory once again. He has carefully analyzed human skulls from around the world and says that they indicate that modern humans evolved from the mixture of small groups that traveled from Africa originally to every continent and intermingled with the native populations. There are similarities in the 30,000 YA skulls from Europe and from Australia that share characteristics with archaic human skulls dating from 40,000 to 200,000 YA
In a related report, scientists have extracted DNA from an Australian human dated at 60,000 YA. An Australian anthropologist Alan Thorne says that this supports the Multi-Regional Theory. They compared the DNA to those of 10 other ancient humans dated from 2,000 to 15,000 YA. They conclude that this DNA is different from that of other fossils and from that of modern humans. And so the debate continues.
Mummy with Wooden Toe
A 3000 YA mummy from Thebes has been found with a prosthetic big toe. The wooden toe is carved with a toenail and was attached with leather thongs to the socket. It was on a woman estimated to be 55 years old at death. The foot showed signs of circulatory problems in the small arteries. Although Egyptians often fitted the dead with prostheses to prepare them for life after death, this one showed signs of wear on the bottom. There is another mummy in the British Museum with a plaster treated linen toe also. This may indicate that they did not rely entirely on potions to cure, but may have done some surgery as well.
Mammoth News
I have been wondering what is happening with the big frozen mammoth find from Siberia and finally there is an article in the February Discover about it. The first wooly mammoth called Jarkov was airlifted from its frozen tomb last year and is being slowly melted and studied. They did get down to the flesh but were disappointed to find that it was like beef jerky indicating that preservation was not as good as they had hoped. The carcass is indeed fragmentary and not well preserved. Sad ends to an exciting adventure. There is another carcass called Hook that they will be digging out this April and they are extending their search. Along with the DNA study to try to determine its relationship to elephants, Ross MacPhee is doing extensive studies to try to prove his theory that some of the great extinctions were caused by viruses. He is searching the DNA and RNA for indications of some super viruses that would have been capable of jumping several species, but not affecting man. He does not believe the current theories that man killed off these large mammals through hunting or that the climate changes killed them off.
New Mesozoic Bird
The Norell/Clarke article in Nature describes Apsaravis ukhaana that lived about 80 MYA in Mongolia. It is very important because it is the earliest of ornithornithine birds ever found. Many enantiornithes birds (called opposite birds because of foot formation) have been found, but they all died out at the K/T. Asparavis has many characteristics of both of these types of birds indicating that the evolution of birds is very complicated. The specimen itself is beautifully preserved and is even in 3-D instead of being flattened.
Predator or Scavenger?
This study from the Journal of Anthropological Research drew me because I am interested in animals as predators or scavengers (especially with the T rex debate). This study concentrates on early humans but some of their results may have some indications for dinosaurs. The extant animals studied were monkeys (chimps and baboons). Some monkeys are known to eat meat occasionally in addition to their normal diet of leaves, fruit and insects. Their digestive system is set up to pass food quickly through the stomach and to process the plant material primarily in the large intestines where enzymes from their own gut bacteria break down the cell walls. Carrion that is quickly contaminated with other bacteria from the saliva of predators, from insects, and from the carcass’ own gut could infect the scavengers large intestine with this alien bacteria. Therefore, after one or two carrion feedings an animal might learn that it can cause intestinal distress causing future avoidance (called the "Garcia Effect"). Indeed, when watched in the wild, monkeys usually only eat meat when they have killed the animal themselves and avoid animals killed by others. This may imply that early homonids might also have followed this pattern. It is believed that early man may have increased the meat in his diet only after fire (1.6 MYA) and cooking made it safe to eat carrion rather than their own fresh kills. Early Homo increased intake of animal fats and proteins to supply the increased energy-expensive brain. There would be a need to extend the diet beyond fruits and roots. Other clues to this behavior are the early tools found at Homo sites indicating the possible cutting of meat and bones for marrow. There are also isotope studies of the teeth and bones that indicate meat eating. Would a T rex have suffered from intestinal distress after eating a day old triceratops and learned to avoid the kills of others? Maybe their stomach acids were strong enough to deal with foreign bacteria? Anyway, I found this study to be interesting and will watch for any follow-ups and reactions from others.
Karen Nordquist, ESCONI Paleontology Study Group
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Last Updated 03/19/01
Number Of Visitors Since 3/23/2005