Afarensis

Dr. Egnor meet Jarle Breivik - a researcher using evolutionary biology to understand cancer. Science Daily has an interesting story on him:

Doing research at the Institute of Basic Medical Sciences, Breivik explores the connection between cancer development and Darwinian evolution. In a recent interview with Scientific American, and the research magazine Apollon, published by the University of Oslo, he concludes that "Cancer is a fundamental consequence of the way we are made. We are temporary colonies made by our genes to propagate themselves to the next generation. The ultimate solution to cancer is that we would have to start reproducing ourselves in a different way."

*snip*

As a medical student at the Norwegian Radium Hospital, Breivik discovered a curious phenomenon. He found that cancer cells that developed in the upper colon had other types of mutations than those found in tumours closer to the rectum. This finding was confirmed by other researchers and could be traced to mutations in particular DNA repair genes. Such genes have evolved to prevent mutations in other genes and play a vital role in defending the organism from cancer. But why do cells in the upper region of the intestine lose a different type of repair mechanism than those further down?

Breivik was determined to find an explanation. After several years of data mining and theoretical modelling, he was able to demonstrate a connection between loss of DNA repair and harmful environmental factors in the intestines. Curiously however, the cancer cells appeared to have lost the repair mechanisms that would protect them from DNA damage in their particular environment. Breivik thus proposed the following hypothesis: Although DNA repair is favourable to the organism; it may not be favourable to the individual cell.

The money quote:

"Deciding when to stop for repairs and when to keep on going is a difficult challenge. Making repairs assures an optimized vehicle, but it also consumes valuable time and resources. At first thought, it may seem obvious that a damaging environment calls for more repair. Paradoxically, however, the effect may be exactly the opposite. Imagine that you are racing through a war zone with constant bombardment. Stopping for repair can then be a fatal strategy, and it is better to keep on going with flat tires and a screaming engine than to stop for repairs," says Breivik.

This illustration thus explains why genetically unstable cancer cells are favoured in hostile environments--such as in the lungs of a heavy smoker.

Or in the brain...read the rest of the article, it is quite interesting.

Meantime, National Geographic and Science Daily both have articles on an interesting study involving early tetrapods and the evolution of biting. The research indicates that biting must have evolved prior to the transition to terrestrial life. From National Geographic:

To investigate the transition from sucking to biting, Markey and colleagues looked at the arrangement of skull bones in living and fossil animals.
"You can think of the skull as a jigsaw puzzle," Markey said. "Individual bones are the puzzle pieces, and the sutures are the edges where they touch each other.
"The shape of sutures can indicate how the skull deforms a little during feeding," she said.
Reporting in this week's issue of the Proceedings of the National Academy of Sciences, the team found that during suction feeding, the skull bones of living fish pull apart at the front and push together at the rear.
"The shapes of the skull sutures reflect these motions," Markey said.
"We saw these same suture patterns, which indicate suction feeding, in a fossil fish but not in the fossil aquatic tetrapod Acanthostega," Markey said.
Study co-author Charles Marshall said: "This suggested that sucking wasn't [the aquatic tetrapod's] primary feeding mode.
"Acanthostega was biting on something," Marshall added, "but we don't know whether it caught food underwater or by ambushing terrestrial prey at the water's edge."

Finally, archaeologists have found what may be the first example of Toltec sacrificing children. According to Reuters:

The bones, dating from 950 AD to 1150 AD and dug up at the Toltecs' former capital Tula, north of present day Mexico City, indicated the children had been decapitated in a group.

The way the children, aged between 5 and 15, were placed in the grave, and the fact they were buried with a figurine of Tlaloc, the God of rain, also pointed to a group sacrifice, archeologist Luis Gamboa said.

"To try and explain why there are 24 bodies grouped in the same place, well, the only way is to think that there was a human sacrifice," he said.

"You can see evidence of incisions which make us think they possibly used sharp-edged instruments to decapitate them."