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Evolution of Hominoids Humans as Hominoids • The Hominoidea can be divided into 2 families: – The Hylobatidae gibbons, referred to as lesser apes. – The Hominidae great apes, humans and our early ancestors • Ponginae orangutans • Homininae gorillas, chimpanzees and humans. The Hominoids Early Hominoids • One of the oldest hominoids found was called Proconsul (named after an ape in the London Zoo called Consul). The oldest fossil is about 27mya others as recent as 17mya It was classified as hominoid because: • • – – – It had no tail. Body and skull suggested it walked along branches and did not swing in branches. The pelvis structure was different. Proconsul Walking Along Branches Early Hominoids • In the middle Miocene deposits (15 – 10mya), many more hominoids were found. – Kenyapithecus from East Africa – Dryopithecus from Europe – this hominoid swung under the trees as modern apes do. – Sivapithecus from South Asia. • But who was the ancestor of the apes and humans? This is still a mystery. “HOMININS, HOMINIDS, HOMINOIDS” WHAT?????? • What is the difference between these terms? • The term hominin is reserved for the primates that are habitually bipedal. • The hominids includes the hominins and the great apes. • The hominoids constitute the superfamily to which the hominins and all the apes belong. The Apes • This group consists of the chimpanzees, gorillas, orangutans and gibbons. • It is believed that the gibbons were the first group to break away from the evolutionary tree, followed by the orangutans. • Gorillas and chimpanzees are the closest to humans, as shown by the similarities of serum proteins. (the amino acid sequence in the chimpanzee’s haemoglobin is identical to that of humans.) The Apes • The gibbons and siamangs are called the lesser apes of the family Hylobatidae. • The other apes are: – Ponginae - orangutans – Homininae – gorillas, chimpanzees and humans. Characteristics of Apes • General • They have no tail. (making sitting more comfortable). • Only apes and humans have 5 cusps on their teeth, and these are arranged so that a “Y” shaped figure can be drawn in the valleys between them. This is called the “Y5” pattern. (Monkeys have 4 cusps). General Characteristics of Apes • Locomotion is by brachiating in the trees and knuckle-walking on the ground (quadrapedal). • They have a semi or fully-erect posture – freeing their hands to manipulate food, handle their young etc. • The arms are long in comparison with their hind limbs. • Their rib cages are flattened from front to back. Remember Brachiation http://www.youtube.com/watch?v=eV-gOL4t9Vk&feature=related Knuckle-Walking General Characteristics of Apes • Their brains are larger than those of monkeys, which allows them to learn quite complex behaviour patterns. • The upper lip is free of the gums allowing the apes to have mobile and expressive faces, so they use facial expressions for communication. • They have powerful canine teeth and large incisors. The Gibbons Characteristics of Gibbons • The smallest apes, the largest being 11-12kgs. • They eat fruit. • 75% of the time they are acrobatic brachiators; the rest of the time they spend quadrapedally or bipedally. • They live in the dense tropical forests of Southeast Asia. • No sexual dimorphism. • An adult male and female may live in a small family group that lasts several years. They have clear boundries to their territories that they defend. The Orangutans Characteristics of Orangutans • Live in the tropical rain forests in Borneo. • They eat fruit. • They brachiate and often hang by their arms, which are very long. They have long curved hands. • They tend to be too heavy to swing from tree to tree so they have to come down on to the ground where they knuckle-walk to the next tree. • They make a new nest to sleep in every night. • Appear to live solitary lives or in small groups centred around females. Gorillas Characteristics of Gorillas • Forest-dwellers which spend most of their lives on the forest floor. • Found in Africa. • Large animals, (females – 90kgs, males180kgs). • The young brachiate, the larger adults stay mainly on the ground. • They forage for food, mostly eating a type of celery and many leaves and shoots rather than fruit. Characteristics of Gorillas • They are nomadic, travelling daily to new feeding areas in groups of about 12 to 20 animals. • The group is dominated by large silverbacked male and there is a strict hierarchy. • They show sexual dimorphism. • They make nests each night. • They young tend to play on their own and the adults spend a lot of time eating. They have not been observed using ant tools. Chimpanzees Characteristics of Chimpanzees • Forest-fringed and open-woodland habitats in Africa. • Males weigh about 45kg. • Knuckle-walkers on the ground and in trees, they brachiate and can walk on 2 legs. • Their main diet is fruit suplemented by insects such as termites. They will hunt and kill small mammals such as baby baboons. • Highly developed visual sense. Each animal looks different and is recognised by its facial features. Characteristics of Chimpanzees • Live in troops of about 20 animals, the basic small group being mother and young; the young remain with their mothers for 4-5 yrs during which time they learn valuable skills and complicated behaviours. • Make a bed of leaves in a tree each night. • Highly intelligent animals, able to fashion tools out of a piece of stick, make wads of leaves to sponge up water from holes in trees, throw stones when frightened or pick up sticks to defend themselves.