Questions and answers provided by Science Line's Dial-a-Scientist on 0345 600444
Monday 02 December 1996
A Fossils of mammal-like reptiles which were around before the dinosaurs show that their teeth were differentiated like today's mammals. Today's reptiles have teeth that are all the same pointed shape. But the early mammal-like reptiles had teeth designed for different purposes - canines and incisors for ripping food apart, molars for grinding it.
Q Why do babies often wake up at night?
A Our sleeping patterns change during our lives. Babies sleep for about 16 hours in 24 while two-year-olds only sleep for nine to 12 hours. Older people can manage with only four to six hours a night. Babies also spend up to 50 per cent of their sleep in a REM state while adults spend only 25 per cent. Babies sleep in short bursts, maximising their chances of feeding by spreading their 16 hours of sleep throughout a 24-hour period. So even if kept awake all day, a baby is unlikely to sleep through the night because it's programmed not to.
Q Do birds get earwax?
A Birds do not have an outer ear and so wax is unlikely to form.
Q Why do we have freckles on the backs of our hands but none on our fingers?
A Freckles are clumps of skin cells with more melanin in them than other cells. Freckles tend to form when our skin is exposed to sunshine. As we walk we tend to hold our hands with our fingers curled inwards, shading them from the sunlight and so reducing the chance of freckles forming.
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