Ancient ear bones offer clues on speech
Researchers debate when language first evolved, but one thing is sure: Language requires us not only to talk but also to listen. A team of scientists now reports recovering the earliest known complete set of the three tiny middle ear bones – the malleus (hammer), incus (anvil) and stapes (stirrup) – in a 2-million-year-old skull of Paranthropus robustus, a distant human relative found in South Africa.
Reported online this month in the Proceedings of the National Academy of Sciences, the researchers found that the malleus of P. robustus, as well as one found earlier in the early human relative Australopithecus africanus, is similar to that of modern humans, whereas the two other ear bones most closely resemble existing African and Asian great apes.
The team is not entirely sure what this precocious appearance of a human-like malleus means. But since the malleus is attached directly to the eardrum, the researchers suggest that it might be an early sign of the high human sensitivity to middle-range acoustic frequencies between 2 and 4 kilohertz – frequencies critical to spoken language, but which apes and other primates are much less sensitive to.
Weddell seal pups born with huge brains
Weddell seals (Leptonychotes weddellii) are the only mammal that dares to swim long distances under sea ice, traveling up to 20 kilometers in hour-long bursts as they scan for air holes and an eventual exit somewhere in the midst of vast Antarctic sheets. There, mothers give birth so that their pups will be safe from leopard seals and killer whales.
But how do those pups learn to navigate the risky underwater terrain so quickly? They’re born with big brains, according to a study published online and in an upcoming issue of Marine Mammal Science. Researchers measured 12 carcasses and found that the brains of newborn pups are 70 percent the size of adult brains – the largest percentage of any mammal. In comparison, the brains of human babies are only 25 percent the size of adults. Good thing our trekking doesn’t start till much later in life.
ScienceNOW is the online daily news service of the journal Science.