SNIPPETS-Oldest find of salmon remains in N America

Salmon fishing in North America dates from the end of the last ice age, a new study reports. In a cooking hearth at the Upward Sun River archaeological site in central Alaska, researchers discovered salmon remains that are 11,500 years old. The hearth sits atop a grave in which two infants were buried.

The remains are the earliest confirmed evidence of salmon consumption in North America, the researchers said. “Before this, we really had no idea that Paleo-Indians were using salmon or fish of any kind,” said Carrin Halffman, an archaeologist at the University of Alaska Fairbanks and an author of the report. “Sites had been dominated by bones of other animals.”

The study appears in the current issue of Proceedings of the National Academy of Sciences. Although about 300 bone fragments belonging to salmon were found, the site represents the beginning of salmon exploitation, said Ben Potter, also an archaeologist at the University of Alaska Fairbanks and a study author. “We’re very excited to get this first evidence,” Ben said. “We don’t know at this point how much they were using it.”

It’s likely that early groups of people captured only small quantities of salmon, possibly using some type of net, he said. The site also provides evidence that the Paleo-Indians consumed other animals, including ground squirrels and hares.

One fish stands watch while another eats

Rabbitfish help one another in a way that had been observed only in mammals and highly social birds, according to a new study. Pairs of these tropical fish will cooperate: While one has its head down feeding in the crevices of coral reefs, the other holds its head at an upward angle, apparently watching for predators.

The fish take turns between feeding and keeping a lookout, said Simon Brandl, a behavioural ecologist at James Cook University in Australia and one of the study’s authors. He added that “When one is down, in 90 percent of cases, the other has its head up.” He and his colleagues reported their findings in the journal Nature Scientific Reports. Simon and his colleagues observed this form of cooperation in male-female pairs and in same-sex pairs — a sign that this is a complex social behaviour.

“If it occurred in only male-female pairs, it makes sense for the male to help out the female to improve fertility,” Simon said. But this behaviour, he added, is an example of reciprocal cooperation, more often seen in mammals like chimpanzees and humans. Fish deserve more attention from researchers studying animal behaviour, Simon said. There are likely to be species even more clever than rabbitfish.