The first "generation" raised on the planet consisted of eight, raised by the seedships single caretaker, Hadracsa. The name denotes gender. Names ending in "csa" are female. Those ending in "ay" are type one males, and those ending in "in" belong to type two males. There are no such sounds in their language, as they do not speak, but sign, so these were created to substitute for their nuances in gesturing which tell others of their species which sex they belong to. Hadracsa raised eight to the age of ten, when they were old enough to help her raise another generation of eight. Ten years later she began a generation of thirty two. As the oldest grew older, the number of young they were expected to raise increased, and their number increased rapidly. To this day the number of offspring a Centaur raises is a measure of success and a source of social pride.
They have three sexes. The female possesses two mating orifices along her flanks and males possess retractible genitalia. Each sex always donates the same portion of genetic code to offspring, unlike humans and Kentaurans. Each donates their third of the data in the same way each time, so children born to the same trio, the centaur social and mating unit, will be identical twins separated only by time. Gestation period is five months (Earth months). A mating trio normally produces three offspring and each becomes the child of a single member. Having more than three is somewhat taboo, an old evolutionary resistance, and a social one. The three are raised separately, but usually spend time around each other, and have a relationship like that of human siblings.
There are two types of trios, mating and social unit. Mating trios are temporary as once each member has a new child the arrangement ends. Social, family, trios are semi-permanent. Each member likely brought children from mating trios and they are raised together.
Centaurs have smooth blue-gray skin. They stand about four and a half to five feet high, and are about as long. Their rear body is horizontally aligned. They have two thick hind legs, which are jointed at the body, once along the length and once at the foot. The forelegs are much thicker than their arms, and are jointed the same as the rear. The feet substitute as hands when needed. They have three stubby short, very strong fingers on each. The arms are thin. The body turns upright, like centaurs of myth, and they have arms which are jointed at the body, twice along the length and again at the hand. They have four regular fingers and an opposable thumb on each side of the palm. Their fingers have an extra joint and are very capable. Their heads curve up from their shoulders, and is smooth and pointy. Almost dolphin like. They have two eyes, binocular vision, and see a spectrum of light very near that which humans see. Their ears are subdermal. Their mouths are not for speaking, just eating. They're omnivores, and have flat bone ridges for grinding as well as individual teeth. They have to chew on the sides of their mouths, the teeth don't pass across the opening.
Centaurs use a sign language which is extremely hard for humans to follow. It's very, very rapid, and uses twelve digits of a different configuration than humans have, so its necessary to watch centaurs to learn since one can't practice it with their own hands. Centaurs can understand human speech with training and almost all of them have had it. They can't respond however, so a person will require a software translator and a CPU to understand without long training. Some centaurs have implants which allow them to speak in a human voice. These are common on mixed crew ships. More to come