Why do animals have so many breasts while humans have just two? SILLY PIG Most animals do not have any breasts. Breasts, or mammary glands, are restricted to mammals, which is where we get the name 'mammal' from. Reptiles, amphibians, fish and birds do not have breasts.
Mammals can have between one and 11 pairs of mammary glands. Generally, mammals which have large litters, such as pigs and dogs, have more mammary glands so they can feed all their young.
Humans and many other mammals which tend to have just one offspring at a time have to make do with just two.
Is size of brain an indication of intelligence? The short answer is no. In humans, the adult brain weighs about 1-1.5 kilograms. An elephant's brain weighs about six kilograms and a whale's weighs more than 10 kilograms. Despite possessing such large brains, neither animal can tie its own shoelaces, let alone explore space or program a VCR.
Humans, with their much smaller brains, are capable of doing all these things and more. What does count, to some extent, is the ratio of brain size to body weight.
The brain of a human is a much larger proportion of his body mass than that of other animals. An elephant's brain may be four times larger than a human's, but an elephant can weigh up to 100 times as much as a human.
If we compare like with like, Neanderthal man (who lived about 100,000-40,000 years ago) had a brain larger than modern man, yet was not very intelligent.