Two million years ago, hominids heard the world very differently from modern humans do, a study said.

Researchers at Binghamton University analyzed the fossilized ear bones of two early hominids from South Africa, A. africanus and P. robustus, which lived 3.3 million and 1.8 million years ago. With computerized tomography scans, they were able to virtually reconstruct the ears and estimate the hominids’ auditory abilities.

“They didn’t hear as well as humans, and they are more like chimps,” said Rolf Quam, an anthropologist at Binghamton University and one of the study’s authors.

There was one exception. From 1 to 3 kilohertz, the hominids had better hearing than modern humans and chimpanzees. “They were almost like superhumans in this range,” Quam said. “They could hear softer sounds than we could.” The findings appear in the journal Science Advances.

 

Rabbitfish eat cooperatively

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 behavioral 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.

Brandl and his colleagues observed this in male-female pairs and in same-sex pairs, a sign that this is a complex social behavior. “If it occurred in only male-female pairs, it makes sense for the male to help out the female to improve fertility,” Brandl said. But this behavior, he added, is an example of reciprocal cooperation, more often seen in mammals like chimpanzees and humans.

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