Yautja

The Yautja - well known as Predators - are a hunting race from the furthest reaches of the universe. The males of the species live for the thrill of the hunt. They also see it as a sport and a mission to earn their "Promise Marks." When in Earth terms, Yautja are best classified as therapsids (sometimes called mammal-like reptiles), this means that they are reptilian creatures that are warm blooded, which may hint at a synapsid-like evolution. Yautja are adapted to hot climates and can allegedly withstand temperatures up to 250°C (482°F). They also possess arthropodian (insect, arachnid, and crustacean) and amphibious features as well. Their mandibles are arthropodian and their skin seems to be scaly like a crocodilian's, but also soft and leathery like an amphibian similar to a frog or salamander.

Biology
Yautja skin is primitive-reptilian, which means they do not possess scales like a Squamatan's (although crocodilian-like scales are found on their backs, arms, back of their hands), but skin like early extinct mammal-like reptiles on earth (Such as Lystrosaurus) The skin is also extremely tough and can withstand temperatures of up to 250°C without being burnt. Although, when faced with colder temperatures, the Yautja skin becomes rigid due to the scales sticking to each other, which makes movement uncomfortable and, in cold enough tempuratures, can even rupture the skin at the slightest movement, causing small lacerations that cannot heal untill they reach a more normalized temperature. It also gives good protection against small caliber weapons (9mm) like a bullet proof vest. Also, due to its unique structure, it somehow tranfers electrical current through the bottom out of the soles of the feet. An interesting adaption, but the conditions for this evolution are unknown even to the Yautja.

Yautja are warm-blooded. Males have an average height ranging between 7 to 8 feet and weigh in at 250 to 350lbs (113 to 159 KG) average and prominent mammary glands like human females. Females have a height range of 6 to 7 feet and weigh between 200 to 280lbs (90 to 127KG).

The skin color has many variations. Ranging from brown-reddish colors right through to bluish-greenish colors. This large variety of colors and patterns probably came about when the Yautja started to settle on other planets. Presumably, their ships were not as fast then as they are now and it would have taken some time just to get to another star system. Yautja on other planet would have been almost cut off from the rest of their species. These Yautja would then start to adapt to this new environment, producing this great variety of colors and patterns. The Yautja circulatory system can be divided in to 3 circulations: In the Yautja circulatory system the brain has a separate circulation. This allows for a higher blood pressure in the rest of the body without damaging the fine network of blood vessels in the brain. This allows the Yautja to live with blood pressures that would normally kill a human.
 * 1. From the heart to the lungs
 * 2. From the heart to the body
 * 3. From the heart to the brain

The ability to create and survive such high blood pressure has certain advantages. The blood can be transported through the body faster and thus oxygen and other nutrients are transported quicker and waste products are removed faster.

This special circulatory system is part of why the Yautja are so strong. It allows the organs and muscles to work harder and thus increase the muscle capacity.

The Yautja's 5-part heart consists of 2 auricles and 3 ventricles. The blood is pumped from the right side of the heart (seen on the left of the heart schematic in blue) through the lungs. From there, it goes back to the heart and into the left auricle (seen on the right of the heart schematic in green). From here it goes in to the 2 ventricles that are connected to it. One pumps it into the body and the other pumps it into the brain at a much lower pressure. When the blood has gone through the body and the brain, it goes back to the right side of the heart and the cycle starts again.

The Yautja skeleton is stronger than our own, although it is made mostly of Calcium, which our bones are constructed of as well. The Yautja skeleton is stronger due to its firm build. The bones are much denser than our own, and are heavier.

Partially due to the oxygen rich blood, the yautja don't seem to have the problem of calcification, a process that makes bones more fragile over time. This also allows the bones to reinforce their structure naturally and also because their body uses more carbon in making the bone, which makes it just as flexible as, and stronger than, human bone tissue, but about 3-4 times more dense and 5-6 times more heavy.

The reason Yautja are much stronger is due partially to the fact that the muscles have a much more efficient nutrient and waste product transport, as well as the much higher gravity on their home planet, and that the muscle fibers are prismoidal and triangular as opposed to a humans round muscle fibers. This makes more muscle able to fit in the same amount of space, and due to the larger size attributes to the greater strength.

The greater strength is also created by the higher percentage of muscular tissue per KG of body weight and the fact that Yautja are bigger than humans.

The Yautja nervous system is almost a replica of human nerves other than DNA and a few structural changes. The nerves use a form of organic fiber optics that allow chemical and electrical signals to travel at speeds up to 20 times faster than a human. Also, instead of remaining relatively close enough for signals to take place, the nerve endings grow past each other and intertwine, allowing for much faster communication.

An interesting thing about the Yautja is their unique DNA structure. Instead of a double helix, the Yautja have a triple helix DNA form. The advantages and disadvantages of this are unknown. Also instead of 4 base pairs like humans, they have 5 base pairs in their DNA. These differences may also have unknown advantages or disadvantages. A recent theory suggests that the "dreads" located on their heads are not actually hair of some sort but infact a unique cooling system designed to allow for survival in their hot environment, the dreads are actually hollow tendrils lined with blood vessels, this allows the heat generated by the Yautja high metabolism to be released easily, the air inside the tendrils acts as an insulator to resist gaining heat from the outside body, this makes them able to resist high temperatures relatively well, it is also useful in cold climates in which the air in the tendrils is heated by the body and retains this heat keeping them from losing to much heat from their tendrils. This is further supported by examination of the head and skull showing the tendrils having sockets in the skull.

Breathing
The Yautja breathe 35% more oxygen than humans due to their larger muscle and metabolism requirements. Due to adverse climates and terrains on their home world, they evolved the ability to breathe hydrogen and a limited amount of carbon dioxide if there is a lack of oxygen in the air. But like humans, they have a limit to how long they can go before their bodies can no longer function without oxygen and a limited time of 10 minutes of breathing carbon dioxide. This allows them to survive in adverse climates on many worlds with limited supplies. Also, due to a larger lung capacity, as an average, Yautja can hold their breath for up to 15 minutes before losing conciousness, whereas a human would be unconcious in two. So a supposed maximum of time before a Yautja would need to breath again would be just under 45 minutes.

Blood
Yautja blood is fairly more resistant to the Xenomorph's acid blood than Humans and it is a luminous phosphor-green colour. Their blood is a base, which neutralises the xenomorph's acidic blood.

Reproduction
Unlike humans, who reproduce the whole year round, the Yautja seem to have a mating season. This makes sense since they have a cycle in their life (though they do not change gender; Xenomorphs do, leading some fans to speculate that Yautja behave similarly).

Interestingly, the Yautja mating season does not seem to be written in stone, as both males and females are capable of reproducing outside the mating season (similar to humans, although our 'mating season' is simply the females' ovulation cycle). Normally, creatures who have a mating season can only reproduce during the mating season. However, it seems that Predators can reproduce the whole year round but won't.

There are 2 theories as to why this behavior exists:
 * 1. Mating season is part of their culture and is sustained for religious reasons or for the sake of tradition.
 * 2. Mating season is simply convenient because of the earlier mentioned distances between males and females.

Mating season is a 30 day period which occurs roughly every 400 days. During the mating season, the males try to mate with as many females as they can. The high ranking males will attract enough females just because of their status. The males that are lower in rank will have to fight for their females. This behavior is probably millions of years old. It is likely that the flat crests on top of a Yautja's head developed for the purpose of attracting a mate. During mating season, a successful male can mate with up to 20 females. This only happens to very successful males who are excellent hunters. For the overall population, 2 or 3 females is a large amount. But because of this type of distribution of females,many males are left without mates. This is also the reason most males don't mate for the first time until they are at least 50 to 60 years old and have acquired a reasonable trophy collection. Sometimes it doesn't happen at all, for instance when a male is seen as unfit for breeding, or when the Yautja becomes dishonorable or cowardly. Sometimes, the lowest hunting males are also unable to acquire a female. These frustrated males may turn on their subordinates.

The Yautja male reproduction system is similar to that of a human male. On the other hand, the female reproduction system differs quite a lot from that of human females. The outside appearance of the female reproductive organs is similar to that of a human, the inner workings are quite different. Although Yautja give birth to live young, the babies develop in an egg like structure. A similar type of reproduction implied by some snakes, which hatch there eggs inside their bodies. This type of reproduction is called ovoviviparous (Ovoviviparous having non-shelled eggs which hatch internally of the female).

In Yautja, this type of reproduction has evolved itself into something much more specialized than just the hatching of an egg inside the body.

In the ovary, only one egg at a time ripens. It takes 40 days and the egg will be ready to be fertilized for the next 70 days. Although the egg is ripe and ready to be fertilized, it is not yet fully grown. It will only grow to its full size when it its fertilized. The egg is fertilized whilst still in the ovary, which will allow it to develop further. When the egg is fertilized, the yolk, which will have to support the growing Yautja fetus, starts to grow in mass. The next 80 days will be crucial. In this period of time, the yolk grows to its full size and the fertilized egg starts to develop into a fetus. Meanwhile, the walls of the "womb" start to produce a thick coating of moist holding slime and blood vessels. This coating will later on provide the growing fetus with oxygen, fluids and a means of removing the carbon dioxide and other waste products. Before this time, the egg gets it's oxygen and water from the albumen. After the first 80 days, the egg has grown to its full size and detaches itself from the ovary. The womb coating will cover it completely within days. The fertilized egg has now become an embryo and the basic shape of the Yautja has revealed itself. The embryo is attached to the yolk by an umbilical cord, it will get its food from here for the next months. From now on, the embryo will keep growing until it has become a baby ready to be born.

Nearing birth, the yolk has shrunk to the size of a Ping-Pong ball, although it isn't round. In the next few hours, the yolk will merge with the embryo's abdomen. When the child is born, the yolk can still be seen as a small elongated bump on the stomach with a slightly different color as the rest of the body.

This type of reproduction has definite advantages over actually laying eggs. The eggs can grow much larger because they don't need a hard shell. The yolk can grow much larger because the amount of albumen needed is reduced immensely. The womb coating provides the oxygen and water that used to be provided by the albumen.

Society
See Yautja (language) for the species' language!

The Yautja society is made up of different classifications, including blooded and un-blooded. Their caste includes:


 * Unblooded - About 25% of male Yautja are unblooded. This means that the Yautja have no distinguishable kills amongst their race, such as killing a Xenomorph. Once a Yautja kills a Xenomorph and collects it's head as trophy, they become blooded. All unblooded are children too young to safely hunt for Xenomorphs, or they simply have not had the chance to battle a Xenomorph yet.
 * Blooded - About 45% of male Yautja are blooded. These are warriors who have gained the clan symbol upon their forehead after their first successful Xenomorph hunt.
 * Retirees - About 10% of male Yautja are retirees, Yautja who have fought their time and now are too old and honoured to hunt. Females commonly come under this section due to their roles as mothers and the driving force behind the homeworlds natural wasteland systems.
 * Elite Predator - Elite Predators are often leaders in their clan, and are only elevated to the caste of Elite Predator once they have acquired a Queen Xenomorph skull. About 15% of blooded Yautja are Elite Predators. Once an Elite Predator they specialize in certain weapons making that weapon their strongsuit. A Brawler specializes in Wirstblades, Spearmaster specializes with the Combistick. Elite Predators often become retirees after a few decades.
 * Clan Leader - Clan Leaders are only made by the Adjudicator's decision. The only way to become a Clan Leader is to clean out an entire Xenomorph hive larger than 300 members in population with a maximum of two others. When this has been proven, the three (or fewer) Yautja all become Clan Leaders. They become the forefathers of that clan and will repopulate with females of their choosing. In order to be elligable for the trials of a hive cleansing, each member of the trio must have at least 3 Queen skull trophies. After this point, any hive cleansings that the forefathers complete will give the clan greater honor and standing in the caste system. Clan leaders comprise 5% of the Yautja society.
 * Adjudicators - The adjudicators are the administrators and law enforcers of the Yautja. They are world leaders and the ruling fist in the overall scheme of the Yautja culture. Less than 1% of Yautja are adjudicators, due to their massive worldly role. At this point, they simply no longer have time to hunt anymore off planet, but often foray into the underground contained hunting grounds, where younger hunters train in order to lend experience to the young ones. Adjudicators are always the leaders of a clan and no adjudicators have ever risen to that position without first having completed at least five hive cleansings.
 * Bad Bloods - These are the criminal Yautja whom have been sentenced to death and escaped. Their justice system shows that crime is very low. About 2% of Yautja are bad bloods. In Predator: Concrete Jungle on the Playstation 2, bad bloods were also Predators captured by humans and brainwashed. They met honorable deaths by their clan brother, the main Predator in the game.
 * Apprentice- These are honorable humans taken by predators to learn the ways of predator
 * Known Predators- Celtic, Chopper, Scar, Wolf, are the only known predators seen throughout the predator sequels.

The Hunt
Male Yautja hunt and because of it some people say they are Predators. When a male Yautja is ready for his first hunt, he is an unblooded Predator. When an unblooded Predator completes a hunt, he is marked and is now a young Predator, also called a Young blood. A Predator has better hunting gear the higher rank he is. When the Predator proves himself worthy enough, the elder will present the Predator the Combi Stick, which is rare in their culture. Other rare items include stronger Plasmacasters, the laser-guided Smart Disc and Razor Whip. Male Yautja hunt on Earth every 100 years. When they kill their first Xenomorph, they use it's acidic blood to form a mark on their helmet and on the head.

Technology
See: Yautja technology  In the game Alien vs. Predator: Extinction, the spear master's armor is made out of Vy'drach, which lives on the infernal deserts of Yautja Prime, surviving heat and radiation strong enough to bake most life forms. If the predator kills the Vy'drach, its hide is made into armour that absorbs heat, plasma and acid to a degree.

Trivia

 * The Yautja's infrared vision coupled with the fact that the Predator seen in Predator 2 makes its base in a large refridgerated warehouse suggest that the original enviroment of the species is somewhere much colder than is hinted at in the series. Thermal vision would only evolve in areas of low enough ambient temperature to make the distinctions between body heat and the heat of the surroundings large enough to see.
 * Thermal vision may also have evolved due to the planet orbiting a high mass red dwarf star. Since red dwarves emit most of their rediation in infrared, it is possilbe that Yautja have eyes which sense IR the same way we sense visible light
 * There is a fair chance that their planet is tidally locked to the parent star i.e. It has no day/night cycle, because it does not rotate on it's axis. This coupled with a low molar mass of Yautja Prime's atmosphere, would allow a wide range of tempretures without compromising habitability.