Pigs
Wild boar
Pigs naturally like to live in forests, especially where there are oak trees that make acorns, because pigs like to eat acorns. At first people hunted wild pigs in the forest. The male wild pigs are called boars. But wild boars are very dangerous to hunt. They are smart and they have long sharp tusks and teeth.
It is much safer to domesticate pigs and have them tame, although even tame pigs can still be very dangerous (still, people are more dangerous to pigs than pigs are to people!). People first began to keep tame pigs about 6000 BC, in West Asia.
Pigs were a very popular source of food all through antiquity, from West Asia all the way to England, from Scandinavia to North Africa. They care for themselves pretty independently, and they will eat apple cores and rotten meat and peapods, so you can feed them on garbage. Pig meat is also relatively easy to preserve by smoking it, like bacon and salami.
But from at least 1000 BC, most people in West Asia, including not only Jews but also other people like the Phoenicians, would not eat pig meat. The Bible says that Jews should not eat pig meat. Some people think that this is because you can get a disease called trichinosis from eating pork that is not cooked enough. The earliest Christians also did not eat pork, but by about 50 AD Christians had decided that this rule did not apply to them.
When Mohammed told the Arabs about the new religion of Islam, he also said that Muslims (people who followed Islam) should not eat pork. So pigs became much less common around the Mediterranean and in West Asia after about 700 AD, and they are still very uncommon today. But in Europe and in China, where people were Christian or Buddhist and not Muslim, pigs remained very common.
Here's a video of a pig:
