The 85-million-year timeline of human evolution

Reconstructing the origins of our species requires many kinds of evidence: fossil and archaeological evidence like bones and artefacts, but also molecular evidence such as ancient DNA, and data on past climates and environments. The pace of discovery has accelerated over the past few decades: the story has been extended further back in time, and has become increasingly complex with the discovery of new sites that hosted our ancient ancestors and new species to add to the human family tree. Because the archaeological record is incomplete, it’s difficult to determine when and where something first appeared, and how long it lasted. The oldest known example of something may be a poor guide to when that thing actually emerged. Hence this timeline often gives wide ranges, and particularly uncertain dates are marked with a question mark. Advertisement 85 million to 55 million years ago Primates – the group that includes monkeys, apes and humans – emerge. The first primates are small and spend a lot of time in trees; they resemble modern tree shrews or squirrels. It’s uncertain exactly when primates first evolve. It may be before or after the extinction at the end of the Cretaceous Period, 66 million years ago, when an asteroid strikes Earth and wipes out many species, including all dinosaurs apart from birds. Genetic studies comparing DNA from different primates suggest they evolve before the extinction. However, primates only show up in the fossil record afterwards – and it’s not always clear they are “true” primates. For instance, a little over 100,000 years after the mass extinction, animals called Purgatorius live in North America. They are plesiadapiforms, closely related to primates. By 55 million years ago, there are unambiguous primates. They include Archicebus, found in eastern China, and several species of Teilhardina, which live in the Americas and Eurasia. It may be significant that Earth experiences a global heatwave called the Palaeocene-Eocene thermal maximum around 55 million years ago. This enables tropical forests to spread widely, giving early primates a huge habitat. 30 million to 13 million years ago The first apes evolve in Africa. Genetics suggests apes separated from monkeys as early as 30 million years ago, but again the fossil evidence comes along later. Rukwapithecus is the earliest known ape or ape-like primate, living 25 million years ago in Tanzania. The 17-million-year-old Masripithecus, from Egypt, may be close to the last common ancestor of all extant apes. Apes do well in Africa for several million years. Kenya is home to Nacholapithecus around 15 million years ago and Nyanzapithecus 13 million years ago. However, apes become increasingly rare on the continent – or at least, their fossils become sparse. 21 million to 16 million years ago Grasses become common in East Africa and savannahs begin expanding in areas that were previously dense forests. This creates a new habitat – but it’s not clear how or when apes and hominins begin living in it. 17 million to 7 million years ago Meanwhile, as early as 17 million years ago, some apes enter Eurasia. There they thrive. Eurasian apes develop more upright postures and curved, grasping fingers – traits we still see in great apes today. Eurasian apes are a diverse bunch. Pierolapithecus lives in Spain around 12.5 million years ago: it has hands that are specialised for vertical climbing, so it probably can’t swing from tree branches. Its contemporary Dryopithecus has similarities to modern gorillas, while Hispanopithecus seems to have been ideally adapted for swinging. The 11.6-million-year-old Buronius may be the smallest ape, weighing just 10 kilograms. 12 million to 7 million years ago Some Eurasian apes may start walking upright, or bipedally. This would mean that a key step in human evolution – the transition to bipedal walking – happened in Eurasia rather than Africa. However, the evidence is disputed, largely because it relies on partial fossils. These include fossils from Danuvius, which lives in Germany 11.6 million years ago and has leg bones that show signs of upright walking. Likewise, the 10-million-year-old Rudapithecus from Hungary has a pelvis that may be adapted to allow a flexible lower back – a key ingredient for bipedal walking. Even if some of these apes did walk bipedally, they are not necessarily our ancestors: bipedality may have independently evolved in multiple groups. 13 million to 5.5 million years ago The last common ancestor (LCA) lives around this time. This unidentified animal is the most recent ancestor of both our closest living relatives – chimpanzees and bonobos – as well as humans and human-like hominins. Some genetic evidence suggests the LCA lives at least 7 million years ago, but it may be earlier than that, 10 million years ago or more – or more recent, just 5.5 million years ago. The population split may be drawn-out rather than sudden. It’s also not clear where the LCA lives. Because the earliest unambiguous hominins are known from Africa, many researchers have assumed an African LCA, but others argue for Eurasia. The fossil record is spotty in both places. Kenya’s 9.8-million-year-old Nakalipithecus may be quite close to the LCA – but unfortunately is only known from one jawbone and a handful of teeth. 7 million years ago Sahelanthropus tchadensis, the oldest known hominin, lives in what is now Chad. Our information about it is limited because we have only a few bones, representing six to nine individuals, all from one small area. The remains include a skull known as Toumaï, fragments of lower jaw and some teeth, one thigh bone (femur) and two upper arm bones (ulnas). Ever since Sahelanthropus was described in 2002, debate has raged about its nature. Some argue it walked bipedally, but others say the evidence doesn’t support that. In turn, some classify it as a hominin, while others contend it is more likely to be an ape. 6.05 million to 3 million years ago Someone, or something, leaves a set of footprints on the tiny Mediterranean island of Trachilos. Some researchers argue the footprints are made by a bipedal hominin, in which case they are evidence that even early hominins venture beyond Africa. However, there is no consensus over who makes them or when. 6 million years ago Orrorin tugenensis lives in what is now Kenya. Their leg bones suggest they are bipedal hominins. Adults are 1.1 to 1.4 metres tall. They still have ape-like arms and curved fingers, ideal for climbing trees. 5.8 million to 4.4 million years ago Hominins known as Ardipithecus live in East Africa. They walk fully upright, but also have grasping big toes like those of great apes, ideal for climbing trees. Their brains remain relatively small and their teeth suggest a varied diet. Two species are known, from different time periods. The earlier species is Ardipithecus kadabba from 5.8 million years ago, which is known from only a handful of remains. It has large canine teeth like those of apes, but evolution causes these to shrink over the next few million years. The second and better-known species is Ardipithecus ramidus, from 4.4 million years ago, represented by a female skeleton dubbed “Ardi”. Ardi is the oldest near-complete hominin skeleton, offering some of our best evidence about the last common ancestor. Initial interpretations claim that Ardi is quite unlike chimpanzees, suggesting the LCA is also not like a chimp, but more recent analyses suggest Ardi’s hands are well adapted for swinging from branches like chimpanzees. 4.2 million to 1.9 million years ago Hominins called Australopithecus live widely in Africa. They retain some ape-like traits, like relatively small brains and long, powerful arms suited for tree climbing. However, their skeletons strongly suggest that they habitually walk on two legs, and there is evidence that they make and use tools. Some Australopithecines may be the ancestors of our own genus, Homo. Multiple species of Australopithecus coexist in Africa. The earliest known is Australopithecus anamensis, which lives in East Africa about 4 million years ago: it may be the ancestor of most or all of the later species. Later, East Africa is home to Australopithecus afarensis. Many individuals of this species are known, the most famous being “Lucy” from the Afar region of Ethiopia. Lucy’s species rubs shoulders with another group called Australopithecus deyiremeda, who have more robust jaws – suggesting they eat tougher food. Australopithecus are not confined to East Africa. In central Africa, in what is now Chad, lives Australopithecus bahrelghazali. Unlike the other Australopithecines, they seem to eat a fairly limited diet, mostly grass. Further species live in southern Africa. One is Australopithecus africanus, exemplified by the Taung Child skull. A famous fossil called “Little Foot” may be the same species but has sometimes been placed into its own species – Australopithecus prometheus. The other South African species is Australopithecus sediba. They live as recently as 1.98 million years ago, meaning they share the continent with some of the earliest Homo – but they retain their Australopithecine traits like long arms for tree climbing. 3.5 million to 3.2 million years ago Kenyanthropus, one of the least understood hominins, lives in Kenya. They are known from a handful of fossils from a site called Lomekwi, including a cranium that is badly squashed. Their cheek bones are fairly pronounced and their teeth small, both of which are more human-like traits. Because there are so few remains, not everyone is convinced that Kenyanthropus is really a separate genus of hominins. 3.3 million years ago The oldest known stone tools are used in Lomekwi, Kenya. The Lomekwian tools are crude, produced by bashing one stone down onto another and knocking flakes off. There are tentative claims of older stone tool use, in the form of apparent cut marks on animal bones. It’s not clear which hominins make and use the Lomekwian tools, or how hominins invent tools; one suggestion is that they first use naturally sharp stones, then find ways to make new ones. 3 million years ago Savannahs, which have been expanding for millions of years, finally reach all the way to southern Africa. Hominins now spend much of their time in mixed environments, with both trees and open grasslands. 2.8 million to 1.4 million years ago Hominins called Paranthropus live in eastern and southern Africa. Given how late in the story they appear, they are remarkably ape-like, with smallish brains. They have dish-shaped faces due to huge chewing muscles and large teeth. Their teeth lead some to dub them “Nutcracker Man”, but the nickname is misleading as they probably don’t eat hard foods, but rather tough and chewy ones like grasses. Three species are known. Paranthropus robustus lives in southern Africa, while Paranthropus aethiopicus and Paranthropus boisei live in the east. The relationships between the species are unclear. However, it does seem that Paranthropus is closely related to Homo. Despite their ape-like bodies, there is growing evidence that Paranthropus make and use tools. Their hands are both strong and dexterous, and their remains have been found alongside Oldowan tools (see below). 2.8 million years ago? The first members of the Homo genus appear in Africa. The earliest fossils are extremely limited: a lower jawbone and teeth from Ledi-Geraru in Ethiopia. 2.6 million years ago The earliest known Oldowan stone tools are used. Named for Olduvai/Oldupai Gorge in Tanzania, they are relatively simple, produced by chipping flakes off pebbles – but still require a degree of coordination, skill and forethought. Oldowan tools are widely and habitually used for over a million years. Palaeoanthropologists have sometimes assumed that Oldowan tools were made only by members of Homo. However, the oldest known Oldowan tools are associated with Paranthropus fossils, suggesting Paranthropus may also use them. 2 million to 1.8 million years ago Homo habilis lives in East Africa. While the species is one of the most famous, its fossil record is highly incomplete so it is not well understood. In particular, we have only partial skulls, and fossils have sometimes been assigned to H. habilis simply because they don’t fit anywhere else. What does seem clear is that H. habilis still has long arms, suggesting they spend a lot of time in trees. H. habilis is often described as the first Homo species. It may have been around before 2 million years ago, but the purported older fossils are so partial that it’s hard to be sure. The Ledi-Geraru jawbone from 2.8 million years ago and an upper jawbone dubbed AL 666-1 from 2.3 million years ago seem to be Homo but don’t quite fit H. habilis. 2 million years ago Earliest evidence of Homo erectus. This species goes on to be one of the most widespread hominin groups and survives for nearly 2 million years. The earliest fossils are found in the Ethiopian highlands and at Drimolen in South Africa. Later, they are also found in North Africa, notably at Tighennif in Algeria around 700,000 years ago. Compared with earlier hominins, H. erectus have significantly larger brains. They have shorter arms and longer legs, making them more like modern humans and less like apes. They also seem to have longer childhoods than earlier hominins, as evidenced by the famous fossil “Nariokotome Boy”. 1.8 million years ago For the first time, some hominins move out of Africa into Eurasia. The earliest widely accepted example is H. erectus, who live in what is now Georgia 1.8 million years ago. Some H. erectus head east, reaching China by 1.7 million or 1.6 million years ago, and going all the way to the island of Java in Indonesia. The Javan population lasts longest, remaining until as recently as 108,000 years ago. Curiously, there is little evidence of H. erectus in western or central Europe, apart from some partial face bones from Sima del Elefante in northern Spain that cannot be confidently identified. There are disputed claims of earlier migrations into Eurasia. Other animals do make the trip, so it may not be all that difficult. 1.8 million to 1.4 million years ago Earliest evidence of hominins using fire, from Wonderwerk cave in South Africa and various sites in Kenya. Similar traces appear at more recent sites in South Africa and the Levant. Some of these early fires may be created opportunistically from wildfires: the oldest hard evidence of hominins starting fires from scratch is from Britain around 400,000 years ago. Hominins may use fires for cooking, which may help fuel the growth of their brains, as cooked food is more nutritious. There is also evidence of hominins using fire to modify stone tools as early as 300,000 years ago. 1.7 million years ago The earliest evidence of Acheulean stone tools, which include hand axes shaped like teardrops and are harder to make than the Oldowan tools. H. erectus may be the first to use them. 1.3 million to 500,000 years ago? Ancestor X – the last shared ancestor of our species (modern humans or Homo sapiens) and our other cousins, the Neanderthals (Homo neanderthalensis) and the Denisovans – lives at this time. We do not know the identity of Ancestor X. Various species have been proposed, including Homo antecessor (see below) and Homo heidelbergensis (see below). But none quite fits the bill. There is also uncertainty about the timing. Comparisons of the genomes of modern humans, Neanderthals and Denisovans suggest Ancestor X lives 500,000 to 700,000 years ago. However, some fossils point to an earlier date. Hominins from Morocco from 773,000 years ago may be close relatives of Ancestor X: they share traits with modern humans and Neanderthals, but also the much earlier H. erectus. More dramatically, a skull from China called Yunxian 2 is between 940,000 and 1.1 million years old. It may be a Denisovan, implying Ancestor X predates this time. 949,000 to 772,000 years ago H. antecessor lives in northern Spain, making it the first hominin known to live in western Europe. The species is known from only one site, the cave of Gran Dolina. There is also a lower jawbone from the nearby Sima del Elefante, which is 1.1 million to 1.3 million years old, but it’s not clear if it’s H. antecessor or another Homo species. H. antecessor has several features seen in later species, including our own, such as flat faces – perhaps hinting that they are our ancestors. 774,000 to 129,000 years ago This is the Middle Pleistocene or Chibanian period, which is sometimes referred to as the “Muddle in the Middle” because the hominin fossil record is so confusing. Many fossil remains, from both Africa and Eurasia, are difficult to categorise. This is exemplified by H. heidelbergensis, first identified from a 609,000-year-old lower jawbone from Mauer, Germany. Various fossils in Europe, Asia and Africa have been suggested to be H. heidelbergensis, but all these claims are disputed and it may be that H. heidelbergensis is solely European. 500,000 years ago Earliest evidence of hominins using pigments, especially the red-orange minerals known as “ochre”. They may first use the pigments to paint their own bodies. Around this time, someone – perhaps a H. erectus – scratches a zigzag pattern into a clam shell on Java, creating the earliest known decoration. Hominins may also be starting to make and wear simple clothes. Key evidence comes from hide scrapers: stone tools used to clean animal hides, a necessary step in making clothing from fur. 476,000 years ago The oldest preserved wooden artefacts: a set of interlocking logs that may have formed part of a large structure such as a building, from Kalambo Falls in Zambia. The oldest known wooden tool, a shaped stick found in Greece, is about 430,000 years old. It’s likely that hominins make and use wooden artefacts long before this, but these have not been preserved, because wood is perishable. 430,000 to 40,000 years ago The Neanderthals (Homo neanderthalensis) live in Eurasia. They make an array of tools and artefacts, including jewellery. They may be the first hominins to make long-term homes. Neanderthals show many signs of human-level intelligence and ingenuity – even making a stone circle deep in Bruniquel cave, France, 175,000 years ago. The oldest known Neanderthal remains are from Sima de los Huesos in northern Spain and are 430,000 years old. Genetics indicates that Neanderthals sometimes interbreed with other hominins, including modern humans (H. sapiens) and the Denisovans of East Asia. While some of the hybrids may struggle with genetic mismatches, enough survive to leave traces in the genomes of all three groups. Many people today have some Neanderthal DNA. The last reliably dated Neanderthal remains are about 40,000 years old, suggesting the species disappears around this time. Many factors may contribute to the extinction, including climate change, the Neanderthals’ small and isolated populations, and the arrival of H. sapiens in Europe. The last Neanderthals live in southern Europe. 350,000 years ago? Modern humans (Homo sapiens) emerge in Africa. The oldest known fossils are from Jebel Irhoud in Morocco and are between 250,000 and 350,000 years old. A skull from Florisbad in South Africa may also be early H. sapiens and is 259,000 years old. Later, there are 195,000-year-old remains from Omo Kibish and 160,000-year-old specimens from Herto, both in Ethiopia. Already, our species is widespread and diverse. 335,000 to 236,000 years ago? Homo naledi lives in what is now South Africa. They are known from only one site: the Rising Star cave. For such a recent species, H. naledi have small brains. Nevertheless, there is evidence that they use fire to cook and make etchings on cave walls. Most controversially, they may bury their dead in the cave, indicating that even small-brained hominins feel the need to commemorate death through ritual. 250,000 to 32,000 years ago? Denisovans live in eastern Asia. They are a sister group to Neanderthals, named for Denisova cave in Siberia where the first fragmentary fossils were found. Denisovans are the first hominins to be identified primarily through ancient DNA. They appear to be large-bodied, with big teeth and thick skulls. However, we still have only limited fossils and few stone tools and artefacts, so our understanding of their bodies and behaviour is limited. It’s also unclear how long they were around and what happened to them: we have only a partial reconstruction of their population history. What is clear is that Denisovans are widespread and diverse. They interbreed with H. sapiens, so today many Asian populations carry some Denisovan DNA. 190,000 to 50,000 years ago? Homo floresiensis, diminutive hominins often known as hobbits, live on the island of Flores in Indonesia. Remains excavated from a cave called Liang Bua show that the hobbits stand barely 1 metre tall and have correspondingly small, but advanced, brains. It’s unclear how and when H. floresiensis evolve. The earliest stone artefacts linked to them are 190,000 years old. The hobbits may be descendants of H. erectus who evolve smaller bodies as an adaptation to island life. A second site on Flores called Mata Menge also has small hominin remains, this time from 700,000 years ago. These may be the ancestors of hobbits. The last traces of the hobbits are from 50,000 years ago, so the species may go extinct around that time. A drying climate and the arrival of H. sapiens may contribute. 134,000 to 50,000 years ago? Homo luzonensis lives on the island of Luzon in the Philippines. Only a few bones and teeth have been found, in Callao cave, so little is known. There is an ongoing debate over their age: as young as 50,000 years old on some measures, at least 134,000 years old on others. 100,000 to 50,000 years ago Modern humans (Homo sapiens) migrate out of Africa and spread around the world. It’s unclear why they do so now; previous migrations may have been unsuccessful as they have left no genetic traces in modern populations. Arabia may be a key crossing point. In Eurasia, modern humans replace the Neanderthals and Denisovans (after some interbreeding). Some get all the way to Australia by perhaps 65,000 years ago – a journey that requires multiple sea crossings. Reaching the Americas takes longer, because it requires settling in the far north-east of Russia and crossing an ice bridge into Alaska. People do this between 33,000 and 14,000 years ago. From there they spread out, some going all the way into South America and the Amazon rainforest. 73,000 years ago and onwards? H. sapiens, and probably other hominins like Neanderthals and Denisovans, create rock art such as cave paintings. Rock art has been found on every inhabited continent. At time of writing, the oldest known cave art is at least 68,000 years old: it is a hand stencil on a cave wall on Sulawesi, Indonesia. The oldest known narrative art, a painting of a pig surrounded by humans, is at least 51,200 years old and is also from a cave on Sulawesi. The oldest known drawing of any kind is a set of red lines daubed onto a loose stone using ochre. The stone was found in sediments in Blombos cave, South Africa, and seems to be 73,000 years old. 40,000 to 10,000 years ago? Around the world, many of the same symbols are repeatedly engraved or painted onto cave walls. The symbols may be a code, intended to convey important information. They are not writing, because they are too limited, but may be a precursor to it: “proto-writing”. 40,000 to 14,000 years ago? Some Eurasian wolves become domesticated, becoming dogs: the first domestic animals. Their bodies become smaller and their canine teeth shrink, among other changes. By about 14,000 years ago, these “incipient dogs” have become modern dogs and there is evidence that humans care for them. Around the same time, some animals begin living alongside humans and getting benefits from doing so, such as food – but they remain wild. These synanthropic animals include foxes, pigeons and gulls. Many other domestications follow, including wheat, chickens and cats (although cats are only sort of domesticated) – but millennia later, after people begin farming. 12,000 to 4000 years ago The Neolithic. Multiple societies begin relying heavily on farming for food, instead of hunting and gathering. This happens in the Fertile Crescent in western Asia, parts of Africa, the Americas, East Asia and Papua New Guinea, within a few thousand years. Some societies start living in dense villages and towns – some of which develop into powerful, hierarchical states. The first true writing systems emerge around 5300 years ago. Ancient caves, human origins: Northern Spain Discover some of the world’s oldest known cave paintings in this idyllic part of Northern Spain. Travel back 40,000 years to explore how our ancestors lived, played and worked. From ancient Paleolithic art to awe-inspiring geological formations, each cave tells a unique story that transcends time.