Extant Apes Review Order Primates Prosimians Lemur Group Anthropoids Tarsiers Loris Group Platyrrhines NWM callitrichids Catarrhines OWM and apes atelids cercopithecoids cebids cercopithecines Hominoids the apes colobines lesser apes gibbons great apes Chimp human common ancestor human bonobo chimp gorillas orangutans Next topic Evolution of the apes and humans Evolution of the ape lineage Catarrhines OWM and apes cercopithecoids Evolution of the human lineage Chimp human common ancestor human bonobo Chimp Hominoids the apes Relative dating Dating Methods recall from archaeology using what is known from material in surrounding strata to infer dates Drawback strata can shift due to geological processes plant processes animal processes etc Absolute dating recall from archaeology using molecular clocks to date fossils Drawback there may not be a good clock for a particular time period or a particular region Genetic comparisons Assuming a constant rate of mutation we can compare DNA sequences to figure out how long ago two species or individuals shared a common ancestor Drawback you have to have an organism s DNA to do it not easy when working with fossils because DNA can decay really challenging with very OLD fossils millions of years Hagen 260 lab class note Linguistic comparisons languages evolve and comparing their features can help us understand when populations diverged more on this later drawback limited to humans Upshot for extant species genetic dating can be used for extinct species fossils relative and absolute methods more common also it s good when data from multiple dating methods corroborate Ape trends How are apes different from OWM the rest of the catarrhines Teeth OWM molars have 4 cusps apes have 5 Locomotor apes brachiate whereas most OWMs walk on all 4s on branches using tails to help balance Suspensory adaptations Shoulder blades scapulae on back instead of side makes for more flexible shoulder joints Short trunks Broad chests left to right that are flat front to back Long arms No tails Evolution of the apes the Hominoids Recall there are a few hundred extant primate species How many extant primates are apes 8 genera genuses of hominoids Lesser apes about 13 species in 4 genera Great apes 4 genera Pongo 2 orangutan species Pan 2 chimp species common chimp and bonobos Gorilla 2 gorilla species though has been contested Homo humans Apes don t comprise a very large fraction of the extant primates but monkeys do Apes evolved in the Miocene epoch Miocene apes Miocene hominoids 23 5mya Early Miocene warm wet climate Late Miocene colder drier climate Early Miocene fossils in Africa from animals that had ape like cranial features e g teeth but monkey like locomotion Middle Miocene 15 10mya many hominoid fossils found throughout Africa Europe and Asia lots of variation in cranial anatomy but clear evidence that they were brachiators Early middle Miocene according to the fossil finds there were a LOT of apes in the world and far fewer monkeys Researchers really cannot infer from which Miocene apes the extant apes descended with the possible exception of the orangutan Late Miocene 10 5mya and into the Pliocene 5mya to 1 8 mya many apes went extinct and were replaced by monkeys this is the same pattern we see today monkeys outnumber apes Evolution and Progress Evolution does not proceed on a slow and steady path toward a particular goal like humanness Boyd and Silk 2006 referring to the ape lineage Despite our tendency to think of ourselves as the pinnacle of evolution the evidence suggests that taken as a whole our lineage was poorly suited to the changing climatic conditions Even though chimps look more similar to gorillas and orangutans they re actually more closely related to humans according to current genetic data The facts most scientists agree on Terminology Most scientists agree on the facts but disagree on how to classify the different apes including humans Some scientists want to classify based on descent only these scientists put humans and chimps in the same group and gorillas in a different group Other scientists want to classify based on descent plus morphology these scientists put chimps and gorillas in the same group and humans in a different group No right answer Hominoids all apes including gibbons everyone agrees on this term Hominins modern humans and their extinct relatives back to the human chimp common ancestor which lived roughly 6mya The hominin fossil record consists of all the fossil taxa that are more closely related to modern humans than they are to any other living taxon It is these extinct taxa plus modern humans that make up the hominin clade the equivalent clade containing modern chimpanzees and bonobos is the panin clade Wood and Lonergan 2008 Note 15 years ago hominid referred to what many now call hominin The term changed after it was discovered that chimps are more closely related to humans than gorillas Skip unless Student Questions What people disagree on is how we should create group classifications based on the facts i e how we should create taxa One camp s philosophy is that we should only use the lines of descent and not group based on morphology by this chimps and humans and all their ancestors back to the common ancestor should be in a group different from gorillas because they are much more genetically related to each other than either is to gorillas Other camps think we should group chimps and gorillas and put humans in their own group based on their morphological traits Neither is necessarily right or wrong the solution is to use which grouping strategy is best suited for exploring a particular scientific problem DNA tells us descent and time distances but the genes that are actually building body parts might just be more similar in chimps and gorillas Evolution descent with modification The chimp human lumpers are more descent oriented The chimp gorilla lumpers are more modification oriented This too is all a Western construct Wood and Lonergan 2008 All apes hominoid All on the red line hominin All on the blue line panin The Chimp human Common Ancestor Chimp human common ancestor Lots of fossils Very few to no fossils human bonobo chimp Recall late Miocene 10 5mya climate change temperatures dropped this continued into the Pliocene 5 1 8mya Tropical forests in Africa shrank and were replaced by drier woodlands and savannas Some of the chimp human predecessors remained in the shrinking rainforests Some left the trees and