Tag: ancient humans

Ancient Seafarers

Special Report: Ancient Seafarers Volume 50 Number 2, March/April 1997
by Peter Bellwood
[image] Map of Southeast Asia and Australia, with present and Ice Age land-sea boundaries, shows the importance of seafaring in this region. Possible routes for the colonization of Australia by modern humans are north, through Sulawesi, and south, crossing from Timor. By 1000 B.C. obsidian from New Britain was reaching Borneo. Indo-Roman pottery reached Bali by the early centuries A.D. (Lynda D’Amico) [LARGER IMAGE]

Southeast Asia and Australia give archaeologists some of the best evidence for ancient sea crossings, not just by Palaeolithic humans but also by Neolithic peoples and even spice traders contemporary with the Roman Empire. New discoveries, some controversial, are pushing back the dates of human colonization of this region and are expanding our knowledge of early island networks. These finds are also illuminating the first steps in some of the longest prehistoric open-sea voyages of colonization on record–from Southeast Asia to Polynesian islands such as Hawaii, Easter Island, and New Zealand, and perhaps also from Indonesia to Madagascar–during the first millennium A.D.

To understand the implications of these discoveries, one must be aware that the Indo-Malaysian Archipelago contains two very different biogeographical regions. The western islands on the Sunda Shelf–Sumatra, Java, Bali, and Borneo–were joined to each other and to the Asian mainland by landbridges during glacial periods of low sea level. Hence they supported rich Asian placental mammal faunas and were colonized by Homo erectus, perhaps as early as 1.8 million years ago. The eastern islands–Sulawesi, Lombok, Flores, Timor, the Moluccas, and the Philippines–have never been linked by landbridges to either the Sunda Shelf or Australia, or to each other. They had limited mammal faunas, chance arrivals from Asia and Australasia.

Migration through the archipelago has always required that humans cross substantial stretches of open sea. But when did they first attempt to do this? There is a current controversial claim by a joint Dutch-Indonesian team that humans were contemporaries of stegodons, extinct elephant-like animals, at a site called Mata Menge on the Indonesian island of Flores. Stone flakes and stegodon bones have been found here in presumed association in deposits located just above a reversal of the earth’s magnetic field dating to 730,000 years ago. Should this claim receive future support we will have to allow for the possibility that even Homo erectus was able to cross open sea, in this case the 15-mile-wide Strait of Lombok between Bali and Lombok.

That the Australian continent was first settled at least 30,000 years ago, by people who had to cross consecutive sea lanes in eastern Indonesia, was well known by the late 1960s. Research by the late Joseph Birdsell and by Geoffrey Irwin of Auckland University suggests that there were separate northern and southern routes, along which most islands would have been visible from their closest neighbors on clear days, leading from the Sunda Shelf islands towards Australia and New Guinea. If Australia was first reached from Timor, as seems likely, then a final sea crossing of about 55 miles, involving movement out of sight of land, would also have been required.

The Australian archaeological record has now been pushed back to the limits of conventional radiocarbon dating, with several sites clocking in between 35,000 and 40,000 years ago. Radiocarbon dates of this age are potentially subject to contamination by younger carbon at levels undetectable in the laboratory. Such contamination can produce a date younger than 40,000 years when the real age is much older. In recent years, optical luminescence dating of sites in northern Australia has raised the possibility that humans arrived there as long as 60,000 years ago, and many archaeologists now accept these new dates. More controversial are current reports, widely publicized in the world media and published in the journal Antiquity, that Jinmium, a sandstone rock-shelter in Australia’s Northern Territory, has stone artifacts more than 100,000 years old. The site’s investigators–Richard Fullagar of the Australian Museum in Sydney and Lesley Head and David Price of the School of Geosciences at the University of Wollongong–used thermoluminescence dating to determine the age of its lower levels. The lowermost stone artifacts are claimed to be more than 116,000 years old. Because the Jinmium dates are from thermoluminescence rather than the more accurate single-grain optical luminescence, many archaeologists question this claim, and verification is essential. Conventional wisdom has always held that the first humans to reach Australia were modern Homo sapiens, but if the Jinmium dates are correct it could be that more archaic forms once lived in Australia, as they did throughout the rest of the tropical and temperate Old World. Indeed, on Java new dates from the Ngandong and Sambungmacan sites suggest that Homo erectus may have survived far longer than previously believed, perhaps to as recently as 25,000 years ago (see “Homo erectus Survival“).

Elsewhere in the Southeast Asian island region, new evidence for early voyaging comes from archaeological projects undertaken in the Moluccas, northern Borneo, and Bali. In the northern Moluccas, between Sulawesi and New Guinea, humans were visiting the coastal caves of Golo and Wetef on Gebe Island 33,000 radiocarbon years ago. Caves and open sites on coastal Sulawesi, northern coastal New Guinea, the Bismarck Archipelago, and the northern Solomons (southeast of New Guinea) have already produced similar dates. At this time people seem to have been very mobile, leaving only sparse traces of occupation (mainly flaked stone tools and marine shells) and not engaging much in trade of raw materials, such as stone for making tools. Many of the islands at this time, especially in the Moluccas and island Melanesia (the Solomons, Vanuatu, and New Caledonia), may have had such limited land faunas that they were unable to support large permanent populations. Those who reached New Guinea and Australia, then joined by a landbridge, might have found a better living hunting now extinct species of large marsupials and flightless birds. Current research at the site of Cuddie Springs near Brewarrina in western New South Wales is demonstrating contemporaneity of humans and megafauna on the Australian continent about 30,000 years ago.

Between 20,000 and 10,000 years ago the Moluccan and island Melanesian archaeological records indicate greater contact and innovation. Obsidian from New Britain was carried to New Ireland (but not apparently as far as the Moluccas) possibly beginning 20,000 to 15,000 years ago. Marsupials were deliberately taken by humans from New Guinea and perhaps Halmahera to stock small islands, presumably for hunting purposes. Cuscuses (nocturnal catlike creatures) were taken to New Ireland, and by 10,000 years ago both cuscuses and wallabies appeared on Gebe. The people of Gebe also built small circular arrangements of coral blocks, too small to have functioned as hut foundations, on the floor of Golo Cave ca. 12,000 years ago. They may have served a ritual function. Several sites in the northern Moluccas, Talaud, and Admiralty Islands have a unique and rather impressive industry of adzes made from shells of large Tridacna and Hippopus clams at about the same date. These adzes suggest that manufacture of dugout canoes was technically possible by 13,000 years ago, although the earliest colonists of these islands probably paddled small rafts. Whatever their craft, the extent and repetitiveness of the earliest colonizations–to as far east as the Solomon Islands via many island-hops by 30,000 years ago–makes some degree of intentionality undeniable.

Many millennia later the Indo-Malaysian region again witnessed remarkable transfers of people and material culture. Three thousand years ago, Neolithic people exchanged New Britain obsidian across 2,400 miles to the site of Bukit Tengkorak in Sabah, northern Borneo. The Lapita people moved it for 2,100 miles eastward from New Britain to as far as Fiji. A new report in the journal Science claims that New Britain obsidian, excavated by archaeologist Stephen Chia of Universiti Sains Malaysia and analyzed by anthropologist Robert Tykot of the University of South Florida, reached Bukit Tengkorak much earlier, by 4000 B.C. No details of the dating are presented, however, and the claim remains unsubstantiated. During the original excavation of this site, by myself in 1987, we recovered a good series of radiocarbon dates and obsidian, identified by Roger Bird of the Australian Nuclear Sciences and Technology Organisation as coming from New Britain. At that time we concluded that the Bukit Tengkorak obsidian dated back no further than 1000 B.C. and was contemporary with the Lapita archaeological culture of the western Pacific (ca. 1500 to 300 B.C.).

As far as Lapita is concerned, my own view, and that of many other archaeologists including Patrick Kirch of the University of California at Berkeley, is that the Lapita culture represents the Austronesian-speaking Neolithic populations that colonized Oceania (Melanesia, Micronesia, and Polynesia) beginning ca. 1500 B.C. These people were ancestral to modern Polynesians and eastern Micronesians, and also ancestral, to a lesser degree because of the prior existence of human populations in the western Pacific, to many of the populations of island Melanesia. In this view, Lapita represents a transmission of people, and Austronesian languages and cultures, into Oceania from Island Southeast Asia, and ultimately from southern China and Taiwan. It is significant that the New Britain obsidian trade, although occurring locally back into the Pleistocene in the Bismarck Archipelago, reached its long-distance apogee in Lapita times.

Opposition to this view of Lapita origins comes from John Terrell of the Field Museum of Natural History, who believes he has found evidence that many cultural features linked with Lapita may have evolved on the northern coast of Papua New Guinea and not in Southeast Asia. At sites near the town of Aitape he has found pottery, so far not precisely dated, which resembles Lapita but lacks its elaborate impressed designs. According to Terrell it also resembles pottery made in Indonesia at about the same time as Lapita, and perhaps even slightly before. Terrell believes that the Polynesian ancestors did not migrate directly from Southeast Asia but were living in northern New Guinea for a very long time before some people finally left Melanesia to colonize Polynesia. However, archaeologists such as myself, who have undertaken research in both Island Southeast Asia and Polynesia, may find this opinion difficult to accept and will certainly demand accurate dating of the new materials from Aitape before giving them serious attention.

We also have dramatic new evidence of sailing ability in the early historical period in Southeast Asia, in this case perhaps involving use of the monsoon winds that blow seasonally across the Bay of Bengal. About 2,000 years ago, pottery characteristic of the Indo-Roman site of Arikamedu in Tamil Nadu, on the Indian coast, found its way to the site of Sembiran in Bali (excavated by I.W. Ardika of Udayana University in Bali), an astounding 2,700 miles as the crow flies, or much more if the sailors hugged the coast. This Indian trade pottery–the largest assemblage ever found outside the Indian subcontinent itself–heralded a millennium of cultural contact that gave rise to the temples and civilizations of Pagan, Angkor, and Borobudur. Much of this trade probably involved spices–even Romans occasionally acquired cloves, which came from small islands in the northern Moluccas.

Future research, if some of the above claims are to attain the status of fact, must involve more thorough dating and more careful attention to the stratigraphic pitfalls that one can fall into, both in caves and open sites. Apparent associations between artifacts, datable materials, and geomorphological contexts can often be deceptive. Furthermore, all the coastal sites that might contain direct traces of Pleistocene colonization were inundated by a rise in the sea level of 325 feet or more after the last glacial maximum. All we see now is the inland geographical skeleton of the former landscape. Underwater archaeology might one day come to the rescue, but so far historical wrecks are proving more attractive, and lucrative, than sunken Pleistocene sites.

Peter Bellwood is a professor in the department of archaeology and anthropology, Australian National University. His research in the Moluccas was supported by grants from the National Geographic Society and the Australian Research Council. A revised edition of his Prehistory of the Indo-Malaysian Archipelago will be published by the University of Hawai’i Press this year.

50,000 years ago people went to sea

In a stunning discovery, a team of archaeologists in Australia has found extensive remains of a sophisticated human community living 50,000 years ago. The remains were found in a rock shelter in the continent’s arid southern interior. Packed with a range of tools, decorative pigments, and animal bones, the shelter is a wide, roomy space located in the Flinders Ranges, which are the ancestral lands of the Adnyamathanha. The find overturns previous hypotheses of how humans colonized Australia, and it also proves that they interacted with now-extinct megafauna that ranged across the continent.

Dubbed the Warratyi site, the rock shelter sits above a landscape criss-crossed with deep gorges that would have flowed with water when Paleolithic humans lived here. From extensive excavations conducted last year, the archaeologists estimate that people occupied Warratyi on and off for 40,000 years, finally abandoning the site just 10,000 years ago.

By analyzing layers of earth in the shelter, the scientists were able to construct a timeline of settlement in the space. They used carbon dating on nuggets of hearth charcoal and eggshells to discover that the shelter was first occupied about 50,000 years ago. They also used a dating technique called optically simulated luminescence (OSL) on buried grains of quartz. This technique determines when those quartz grains last saw sunlight and heat. Both techniques returned similar dates, adding to the researchers’ confidence in their findings.

This makes Warratyi the oldest evidence of human occupation in the arid Australian interior, long believed too hostile for ancient people who had few tools. But these findings make it clear that the ancestors of Australia’s indigenous people were, in fact, seasoned explorers who could survive in difficult conditions.

Genomic evidence for the Pleistocene and recent population history of Native Americans

Science DOI: 10.1126/science.aab3884

Maanasa Raghavan1,*, Matthias Steinrücken2,3,4,*, Kelley Harris5,*, Stephan Schiffels6,*, Simon Rasmussen7,*, Michael DeGiorgio8,*, Anders Albrechtsen9,*, Cristina Valdiosera1,10,*, María C. Ávila-Arcos1,11,*, Anna-Sapfo Malaspinas1* et al.

How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we find that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (KYA), and after no more than 8,000-year isolation period in Beringia. Following their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 KYA, one that is now dispersed across North and South America and the other is restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative ‘Paleoamerican’ relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model

Dogs have been around for at least 27,000 years


This image compares an ancient Taimyr Wolf bone from the lower jaw to a modern pipette.
Credit: Love Dalen

Dogs’ special relationship to humans may go back 27,000 to 40,000 years, according to genomic analysis of an ancient Taimyr wolf bone reported in the Cell Press journal Current Biology on May 21. Earlier genome-based estimates have suggested that the ancestors of modern-day dogs diverged from wolves no more than 16,000 years ago, after the last Ice Age.

The genome from this ancient specimen, which has been radiocarbon dated to 35,000 years ago, reveals that the Taimyr wolf represents the most recent common ancestor of modern wolves and dogs.

“Dogs may have been domesticated much earlier than is generally believed,” says Love Dalén of the Swedish Museum of Natural History. “The only other explanation is that there was a major divergence between two wolf populations at that time, and one of these populations subsequently gave rise to all modern wolves.” Dalén considers this second explanation less likely, since it would require that the second wolf population subsequently became extinct in the wild.

“It is [still] possible that a population of wolves remained relatively untamed but tracked human groups to a large degree, for a long time,” adds first author of the study Pontus Skoglund of Harvard Medical School and the Broad Institute.

The researchers made these discoveries based on a small piece of bone picked up during an expedition to the Taimyr Peninsula in Siberia. Initially, they didn’t realize the bone fragment came from a wolf at all; this was only determined using a genetic test back in the laboratory. But wolves are common on the Taimyr Peninsula, and the bone could have easily belonged to a modern-day wolf. On a hunch, the researchers decided to radiocarbon date the bone anyway. It was only then that they realized what they had: a 35,000-year-old bone from an ancient Taimyr wolf.

The DNA evidence also shows that modern-day Siberian Huskies and Greenland sled dogs share an unusually large number of genes with the ancient Taimyr wolf.

“The power of DNA can provide direct evidence that a Siberian Husky you see walking down the street shares ancestry with a wolf that roamed Northern Siberia 35,000 years ago,” Skoglund says. To put that in perspective, “this wolf lived just a few thousand years after Neandertals disappeared from Europe and modern humans started populating Europe and Asia.”


Story Source:

The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.


Journal Reference:

  1. Skoglund et al. Ancient wolf genome reveals an early divergence of domestic dog ancestors and admixture into high-latitude breeds. Current Biology, 2015 DOI: 10.1016/j.cub.2015.04.019

Cite This Page:

Cell Press. “Our bond with dogs may go back more than 27,000 years.” ScienceDaily. ScienceDaily, 21 May 2015. <www.sciencedaily.com/releases/2015/05/150521133626.htm>.

Ancient Tools….

Stone tools now 3.3 million years old

Sonia Harmand presented a talk at the Paleoanthropology Society meeting this week describing her team’s discovery of stone tools in a 3.3-million-year-old context at Lomekwi, on the west side of Lake Turkana. Michael Balter reported on the talk in a story in Science: “World’s oldest stone tools discovered in Kenya”:

In 2011, Harmand’s team was seeking the site where a controversial human relative called Kenyanthropus platyops had been discovered in 1998. They took a wrong turn and stumbled upon another part of the area, called Lomekwi, near where Kenyanthropus had been found. The researchers spotted what Harmand called unmistakable stone tools on the surface of the sandy landscape and immediately launched a small excavation.

The story discusses the contents of the talk, that the tools have been found both from surface and excavation contexts. According to the article, the artifacts show quantitative differences from known Oldowan assemblages, all of which are at least 700,000 years more recent. These differences led Harmand and colleagues to name a new tradition, which they are calling the “Lomekwian”.

I can’t really comment more informatively about this until the work is published so that I can evaluate it. The obvious implication is that stone tools were invented and used by multiple lineages of early hominins. Just as there were different styles of body shape and bipedal mechanics among early hominins, there were likely different styles of technical traditions. A few of these were stone, but almost certainly there were perishable tool traditions among most populations of early hominins. Just taking what we know from living chimpanzee populations, with different traditions of tool use, complex tool sets made from perishable materials, and occasional use of durable objects made from stone. All hominins added initially was the deliberate flaking of stone to make objects recognizable in the archaeological record.

That is to say, humans have elaborated upon a technical ability that is latent among all the apes. This technical ability rests upon social learning skills that are necessary in chimpanzee societies, and early hominin societies inherited those skills from the common ancestors of humans and chimpanzees. After millions of years of exploring this technical space, some experiments led to the manufacture of stone flakes and choppers. Possibly one or more experiments led to the manufacture of bone points or piercers, as evidenced at Swartkrans and Kromdraai, and often attributed to robust australopithecines.

Such traditions may or may not have been shared across different hominin populations. In chimpanzees, technical traditions are not widely shared, yet we know that they may last locally for at least a few thousand years. If a chimpanzee-like model applied across the Pliocene, traditions that lasted a few thousand years across local areas would occasionally be visible to archaeologists, if they were looking for them.

Now they are.

Ice Age Population

Ice age Europeans on the brink of extinction

Ice-age Europeans roamed in small bands of fewer than 30, on brink of extinction (Horizon magazine)

In some cases, small bands of potentially as few as 20 to 30 people could have been moving over very large areas, over the whole of Europe as a single territory, according to Professor Ron Pinhasi, principal investigator on the EU-funded ADNABIOARC project.

This demographic model is based on new evidence that suggests populations were much smaller than is generally thought to be a stable size for healthy reproduction, usually around 500 people. Such small groupings may have led to reduced fitness and even extinctions.

‘As an archaeologist and anthropologist, I was quite shocked to see how limited, how small the population numbers were. You know, shockingly small,’ said Prof. Pinhasi, based at University College Dublin, Ireland.

Prof. Pinhasi’s team has found that the genomes sequenced from hunter-gatherers from Hungary and Switzerland between 14 000 to 7 500 years ago are very close to specimens from Denmark or Sweden from the same period.

These findings suggest that genetic diversity between inhabitants of most of western and central Europe after the ice age was very limited, indicating a major demographic bottleneck triggered by human isolation and extinction during the ice age.

‘We’re starting to be able to reconstruct the actual dynamics of migrations and colonisation of the continent by modern humans and that’s never been done before the genomic era,’ explained Prof. Pinhasi.

He believes that early humans crossed the continent in small groups that were cut off while the ice was at its peak, then successively dispersed and regrouped over thousands of years, with dwindling northern populations invigorated by humans arriving from the south, where the climate was better.

‘You see a real reduction in population numbers and diversity, so you see the few lineages that probably split or separated before the ice age, and then stayed isolated during the ice age,’ he said. ‘Some time after the ice age, they kind of re-emerge, or disperse, and get together, as we see new contributions to European lineages from Asia and in particular the Near East.’

Cave Paintings

Maybe you’ve seen the film “Cave of Forgotton Dreams.” That’s Werner Herzog’s study of cave paintings in Europe, amazing, stunning, ancient artwork found deep in the earth. Until very recently Europe was the only place such sophisticated art was found, forming the basis of the argument (promulgated of course by European experts) that human modernity is demonstrated by symbolic thought and hence because art is symbolic and the cave art is the most sophisticated, “modern” humans first arose in Europe.

Well…..Nature Magazine now reports this:

A hand painted in an Indonesian cave dates to at least 39,900 years ago, making it among the oldest such images in the world, archaeologists reported Wednesday in a study that rewrites the history of art.The discovery on the island of Sulawesi vastly expands the geography of the first cave artists, who were long thought to have appeared in prehistoric Europe around that time. Reported in the journal Nature, the cave art includes stencils of hands and a painting of a babirusa, or “pig-deer,” which may be the world’s oldest figurative art.

 

Earliest Evidence of Offshore Fishing

This article discusses evidence found off Timor that humans went offshore after fish a long long time ago. I’ve always thought humans were capable seafarers right from the start, I mean, the very start. It’s not an easy thing, to head offshore miles after fish in deep water, but people did it tens of thousands of years ago. This leads me, at least, to think that humans traveled all over the word along the coasts well before overland.  Marine conditions can be bad, but if I had to choose between wandering the uplands being stalked by short face bears, dire wolves, saber tooth cats, and huge lions, or heading to sea in a well made big canoe, with line and some hooks for food, I know what I’d do. What wuld you do?

Oldest evidence for deep-sea fishing found

The world’s oldest evidence of deep sea fishing has been discovered by an Australian research team, showing that our regional ancestors mastered the skill some 42,000 years ago.

fishhook

Example of one of the shell fishhooks found. Credit: Sue O’Connor

Jerimalai cave

The Jerimalai cave in East Timor. Credit: Sue O’Connor

FAREHAM: The world’s oldest evidence of deep sea fishing has been discovered by an Australian research team, showing that our regional ancestors mastered the skill some 42,000 years ago.

For decades archaeologists have wondered about the maritime skills that early humans possessed when they reached Australia by sea 50,000 years ago. Now, Sue O’Connor and her team from the Australian National University (ANU) in Canberra have reported the earliest evidence that these first colonists were skilled at pelagic, or deep sea, fishing.

The team excavated Jerimalai cave in East Timor, uncovering thousands of well-preserved animal and fish bones as well as stone tools and shell beads. They also discovered the world’s oldest fishhook, made from a shell and dating back to between 23,000 and 16,000 years ago.

“We believe this is the earliest known example of a fishhook and shows that our ancestors were skilled crafts people as well as fishermen. The hooks don’t seem suitable for deep sea fishing, but it is possible that other types of hooks were being made at the same time,” said O’Connor, lead author of the study published in the current issue of Science.

Fish on the menu

O’Connor’s team found more than 38,000 fish bones from 2,843 individual fish during the excavation. They showed that fish was the staple diet of the earliest dwellers of Jerimalai, making up 56% of the animal remains uncovered and the majority of the fish bones were from deep-sea species such as tuna. Other fish on our ancestors’ menu included parrotfish, groupers, triggerfish and snappers. There is also evidence that they ate sharks, marine turtles and a wide range of shellfish.

“What the site in East Timor has shown us is that early modern humans in Island Southeast Asia had amazingly advanced maritime skills. They were expert at catching the types of fish that would be challenging even today – fish like tuna. It’s a very exciting find,” said O’Connor.

What’s still unknown is how these ancient people were able to catch these fast-moving deep-ocean fish, but it is clear that they were using sophisticated technology and watercraft to fish offshore.

“These discoveries provide important evidence that the earliest colonisers of Australia had advanced knowledge and skills in stone, bone and wood technology,” commented Nina Kononenko from the University of Sydney. “They were able to build reliable water-crafts, manufacture fishing gears and other tools, as well as items for their subsistence and maritime adaptation as early as 40,000 to 45,000 years ago.”

Solving an enduring puzzle

The team’s findings also indicate that the proportion of deep-sea fish in the diet steadily declined over the millennia, making up just 24% of the total by 5,500 years ago, implying that this type of fishing became less common over time.

These findings may also help shed light on how Australia’s ancient ancestors originally arrived on the continent. It has long puzzled archaeologists that the boats used by indigenous people in Australia when the first Europeans made contact were very simple rafts and canoes. How did they make sure a daunting crossing using such simple boats? The research suggests that the early colonists had advanced maritime skills and technology when they arrived, but that these were gradually lost. “In Timor there was very little in the way of large land-dwelling fauna for the early colonists to eat – mostly rats and bats, snakes and small lizards – so this could have honed their maritime skills,” O’Connor said.

“But the sites that were on the coast 50,000 – 40,000 years ago became submerged as sea level rose at the end of the Pleistocene. And, when they settled, the early Australians would have found a wealth of marsupial fauna – an easier food source than deep-sea fish. So perhaps coastal resources would not have been as attractive to them and over time people lost their maritime skills.”

Capacity to invent technologies

The finds from the Jerimalai cave site demonstrate that 42,000 years ago our regional ancestors had high-level maritime skills, and by implication the technology needed to make the ocean crossings to reach Australia. It also helps to show how modern humans may have travelled to the Sahul, the landmass that was made up of Australia, Papua New Guinea and the Aru Islands during the Pleistocene epoch.

This is a very exciting find indeed,” said Nick Barton, professor in palaeolithic archaeology at the University of Oxford in England. “It provides some of the oldest tangible evidence for sea fishing using line anywhere in the world and offers growing support for an early southern route into the Sahul by seafaring modern humans. It also stokes the current controversy over Homo floresiensis. Why did modern humans apparently not use Flores as a stepping stone island en route to Australia?”

“The humble fish hook discovered by the ANU team is testimony to the extraordinary capacity of our direct ancestors to invent technologies and develop new behaviours to deal with unfamiliar environments as they encountered them,” added Graeme Barker, professor of archaeology at the University of Cambridge in England. “This ‘adaptive plasticity’ appears to have been the main reason why they were able to out-compete other hominin species, such as the Neanderthals of Europe and the ‘Hobbits’ of Flores, so successfully.”

More information:
Original paper in Science

A great article by John Hawkes – johnhawkes.net

 Launching genetic diversity to the stars

Popular Mechanics asks, “How Many People Does It Take to Colonize Another Star System?”. The basic problem is that a multigenerational star voyage requires the trekkers to mate and reproduce many times while maintaining a limited population size. Too few people, and the colonists will rapidly lose genetic diversity by genetic drift.

The article starts by noting the work of anthropologist John Moore on the question. Moore concluded that the social structure necessary to prevent inbreeding was essentially that of clans or extended tribes of hunter-gatherers — strong kin avoidance rules to prevent inbreeding and a population size of 150-300 people.

A new paper by Cameron Smith focuses instead on the worst case scenarios, concluding that the “safe” population size would be much higher:

Entire generations of people would be born, live, and die before the ship reached its destination. This brings up the question of how many people you need to send on a hypothetical interstellar mission to sustain sufficient genetic diversity. And a new study sets the bar much higher than Moore’s 150 people.

According to Portland State University anthropologist Cameron Smith, any such starship would have to carry a minimum of 10,000 people to secure the success of the endeavor. And a starting population of 40,000 would be even better, in case a large percentage of the population died during during the journey.

A number as large as 40,000 people would enable the mission to approximate the effective population size of the entire human population of earth before 100,000 years ago or so. For reasons I’ve discussed many times (for example, “Cultural impedance, demographic growth, effective population size”), the effective population size of humans does not mean that the actual number of people in the ancestral human population was very small. With Pleistocene people, there were many processes that reduced the genetic diversity (and hence our estimates of effective population size) within a population of a relatively large actual population size — on the order of a few hundred thousands of people.

Forty thousand is pretty small, but on a random-mating voyage of a hundred generations should basically approximate the Wright-Fisher population model. Smith further examines scenarios in which “catastrophic” events may affect the mission, greatly reducing genetic variation (or eliminating it). In these scenarios, a population dispersed across multiple “ships” would create a buffer, but each of those units has its own small population size issues, arguing for a bigger mission.

I’ll take a deeper look at Smith’s upcoming paper after the AAPA meetings. These future scenarios really help us think about the limits that existed in past human populations, which were less constrained in some ways but more so in others. Moore’s approximations for a future “generation ship” mission incorporated social dynamics in ways that have clear parallels in the past (his ethnographic work focused on small village societies of Southeast U.S. native peoples). Smith’s simulations refer to a larger-scale aspect of genetic drift.

The interaction of these two factors does not easily reduce to equations, but creates the most interesting anthropological questions. How much social control is necessary to maintain the viability of a colonizing population, not only genetic viability but also cultural viability? What is the balance between shared goals and practical needs?

I question the general assumption that such a mission would “need” to maximize the genetic diversity of the colonists. In fact, many potential groups of interstellar colonists might prefer to reduce their genetic diversity.

Imagine a small group of people with the sufficient motivation to divorce themselves from humans on Earth, launch across interstellar space for thousands of years, forcing their descendants to live within a tiny habitat, with the expectation that their common offspring will colonize a new planet a hundred generations hence. The kind of internal discipline necessary to motivate such a scheme is more like a cult than an open society.

Cults enforce cooperation by means of social isolation,

By increasing the relatedness of the population, they could enhance the incentives for cooperative behavior. In effect, people boarding the voyage on Earth would be assured that their descendants would not merely be notional descendants but in fact strongly genetically similar to them. Such groups don’t want to board this ship with a random selection of humanity; they want to board with their cousins. That reduced level of genetic variation would generate a larger genetic payoff for each individual launching from Earth.

They are not going to create a microcosm of Earth’s genetic variation. They’re going to create a colony of clones.

UPDATE (2014-04-05): A number of Twitter commentators have suggested that you don’t need to have so many people if you have a store of frozen sperm and egg cells. In essence, you could create a human version of the Long Term Evolution Experiment run by Richard Lenski. By unfreezing the eggs and sperm of previous inhabitants — or unrelated eggs and sperm brought from Earth — the colonists could add whatever genetic variation is required, or “rewind” the colony to a previous gene pool.

That can be done with today’s technology. We may question whether freezing is really a viable strategy across 1000 years. As yet we only know that freezing works over 20 years or so, and we don’t have good statistics yet about whether germ cells or embryos frozen over longer time periods have any increased chance of mutations or other long-term effects. Still, the level of risk already faced by interstellar voyagers is likely much larger than a slight increase in risk from long-term freezing of germline tissue.

It would make perfect sense to have a large store of adaptive variants available to deal with whatever challenges the colonists face on their new world. Imagine that they settle a world with only two-thirds of Earth’s sea-level atmospheric pressure. An influx of frozen Tibetan sperm would bring in genes to adapt the colonists to their hypoxic world.

Of course, we may also consider that a starship 50 or 100 years from now will be leaving an Earth with vastly greater genetic engineering potential than we currently possess. Colonists after the ninety-eighth generation might vastly prefer a bit of genetic tinkering to their own gene pool, instead of unfreezing vastly different DNA from an Earthling stranger. In that sense, the colonists will not need either a large population or a giant frozen sperm vat. They can build as they go.

This brings us back to social dynamics. The colonists must maintain their motivation and ability to put the colonization plan into motion as they arrive at their destination. Death of the colony is not the only risk; their culture may slowly devolve until they are nothing but interstellar lotus-eaters. We don’t know how large a cultural group is necessary to maintain the necessary traditions over a thousand-year voyage.

That seems like an interesting problem.

I think Mr. Hawkes is onto something. I think the biggest problem here is cultural, the danger that memory will be lost and myths and legends arise that lead people to forget where they are going or why. Heck, none of us has a clue what our great grandparents were like or what they did. That’s three generations back. Imagine 100 of them. That’s 2,000 years. I can see a bunch of properly selected and evaluated stable colonists sent off and three hundred years later the ship filled with some kind of magic and myth entirely unrelated to what the purpose originally was.