Some diets are so specialized that the entire body form evolves to accommodate them. The slow-moving and solitary antman has claws for tearing open anthills, a long middle finger for reaching into the tunnels, and a startling coloration to warn enemies that its flesh is not good to eat. Extreme adaptation has lost the antman the sharp teeth and nails of its woodland-dwelling ancestors. Instead the antman's defense is its vivid coloration and its specialized diet.
A long finger probes and gropes down the tiny tunnel into the nest. The loose soil and twigs are forced apart by the bladelike fingernail and the finger slides in, deeper and deeper. Ants, enraged by the intrusion, swarm out of side-chambers and tunnels, and mass against the attacker. Stings and jaws sink into the tough skin, but make little impression. Courageous fighters hang onto the invading flesh as their blind instincts dictate, while others climb over them to find other spots to attack. Soon the whole finger is a clump of swarming defenders.Up above, the antman has gauged that enough time has elapsed, and pulls his hand with its long finger from the nest. It is a black mass of ants. He has judged the timing correctly - just enough time for the ants to attack his finger in sufficient numbers, but not enough for them to abandon the defense as useless. He did not feel the assault on his finger, since it has no nerves that would detect pain. The whole finger, with its attached ants, goes into his mouth and is then withdrawn slowly, his tiny teeth scraping the insects from the skin. He swallows the ants, a number of which saw the danger in time and abandoned the finger, and are now crawling over his face. They do not trouble him: he can close off his nostrils and his eyes as they come close, and when his mouth is empty he wipes them from his face with the back of his hand and his long tongue.
He turns back slowly to the nest. With the huge claws on two of his fingers (those that were once called the thumb and index finger) he rips the covering off another part of the nest. Patiently he waits for the defenders to swarm up once more, and inserts his long middle finger again into one of the passages.He is rather a solitary creature. The ants that he eats are highly nutritious, but it takes a great deal of them to make a meal so a single anthill could hardly sustain two antmen. His movements are also very slow and deliberate. He has no natural enemies, although he evolved at the same time as many of his cousins developed into hunting, flesh-eating types. His defense is in the food that he eats. He is immune to the poisons of the formic acid in the ants' stings, but his body does not break them down; instead it redeposits them in his tissues, making his flesh unpalatable to any flesh-eating carnivore. His fine black fur has a glaring white stripe across the back and down the legs. Any flesh-eater that sees this striking pattern realizes that its owner is not good to eat.
Once upon a time, millions of years ago, there were other animals that pursued this very way of life. They inhabited all the continents, but each place had its own unrelated species. The anteaters of old South America and North America were no kin to the aardvarks of Africa, and they only looked like one another because they pursued the same lifestyle. They possessed similar bodily features that had the same functions (long sticky tongues, narrow mouths, heavy claws) but evolved independently. Likewise neither of these animals was related to the marsupial numbat of Australia, a mostly termite-eating mammal of similar appearance. The whole concept of the same shapes cropping up in unrelated animals that lived in the same way was what the zoologists once termed "convergent evolution".
Now all the anteaters, the aardvarks and the numbats have been extinct for 3 million years, yet their food has remained: there are still ants and termites all over the world. It is the way of nature that if a food supply exists then a creature will evolve to exploit it, usually emerging from a group of fairly unspecialized animals. In this case, the most unspecialized animals around were the humans genetically engineered to live on the wide range of food of the temperate woodlands. Consequently, over the last few million years these omnivores have developed, under the natural influences of selection, to become specialized feeders in the various different environments present. One group has developed into the ant-eaters.
By 5 million years (the 50020th Century)
They are wiped out by the Travelers of the stars.