Monday, January 19, 2015

At BioLogos, Stephen Meyer Clarifies the Disagreement Separating Intelligent Design from Theistic Evolution - David Klinghoffer - January 19, 2015

At this website by various means we seek to defend life, to encourage Christian faith, to promote Catholic tradition, to edify Marriage in its link to the Creator, to encourage families and individuals, and to support missionary disciples of Jesus. G.S.

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https://evolutionnews.org/2015/01/at_biologos_ste/

At BioLogos, Stephen Meyer Clarifies the Disagreement Separating Intelligent Design from Theistic Evolution

David Klinghoffer @d_klinghoffer January 19, 2015, 4:53 PM

The theory of intelligent design has supporters and detractors both among religious believers and among atheists and agnostics. An atheist sympathizer like Thomas Nagel, the renowned New York University philosopher, is an interesting case. No less so are those Christians and Jews who dislike the idea, despite the fact that traditional theism prompts us to expect objective evidence of design in nature.

Regarding the latter and their style of critique when it comes to ID, I think you could advance a two-part hypothesis: Religious believers who are not familiar with the relevant science feel free to criticize ID on scientific grounds. However those who do know the science are more likely to reject ID not on scientific but on theological or philosophical grounds. That is rich with implications.

Currently at the theistic evolutionary website BioLogos, Discovery Institute’s Stephen Meyer helps clarify this. BioLogos published a series of critical reviews of Meyer’s book, Darwin’s Doubt, and graciously invited him to reply. Dr. Meyer writes:

I have especially appreciated how the reviews in this recent series have unexpectedly clarified the nature of disagreement between proponents of the theory of intelligent design (ID) and the proponents of theistic evolution (or evolutionary creation) associated with BioLogos. I — and many others — have long assumed that the debate between our two groups was mainly a scientific debate about the adequacy of contemporary evolutionary theory. Surprisingly, the reviews collectively have shown that the main disagreement between ID proponents and BioLogos is not scientific, but rather philosophical and methodological.
In particular, the reviews have revealed that the central issue dividing the BioLogos writers from intelligent design (ID) theorists concerns a principle known as methodological naturalism (MN). MN asserts that scientists must explain all events and phenomena by reference to strictly naturalistic or materialistic causes. The principle forbids postulating the actions of personal agency, mind, or intelligent causation in scientific explanations and thus limits the explanatory toolkit of science to strictly material processes or physical causes. The principle of methodological naturalism is, of course, not a scientific theory nor an empirical finding, but an allegedly normative methodological rule, against which I have argued in depth, both in Darwin’s Doubt (see Chapter 19) and in my earlier book, Signature in the Cell (see Chapters 18 and 19). My colleagues have also argued against MN in their responses to some of the BioLogos reviews of Darwin’s Doubt (see, for example, here and here).
Recall that Darwin’s Doubt argues that intelligent design provides the best explanation for the origin of the genetic (and epigenetic) information necessary to produce the novel forms of animal life that arose in the Cambrian period. In making this case, I show first that neither the neo-Darwinian mechanism of natural selection acting on random mutations, nor more recently-proposed mechanisms of evolutionary change (species selection, self-organization, neutral evolution, natural genetic evolution, etc. — see Darwin’s Doubt Chapters 15-16) are sufficient to generate the biological information that arises in the Cambrian period. Instead, I show — based upon our uniform and repeated experience — that only intelligent agents have demonstrated the power to generate the kind of functional information that is present in biological systems (and that arises with the Cambrian animals). Thus, I conclude that the action of a designing intelligence provides the best ("most causally adequate") explanation for the origin of that information.
Now, one might have expected that Ralph Stearley, a paleontologist, and Darrel Falk, a geneticist, both of whom have extensive knowledge of evolutionary theory, would have critiqued the main scientific argument of Darwin’s Doubt on scientific grounds. In particular, one might have expected that they would have argued that either the neo-Darwinian mechanism, or some other evolutionary mechanism, does have the creative power to produce the information necessary to build new forms of animal life. Instead, except for raising a few minor objections about incidental scientific matters, both acknowledged that evolutionary theory has left the problem of the Cambrian explosion unsolved — i.e., that the mutation/natural selection mechanism lacks the creative power to account for macro-evolutionary innovations in the history of life.

As Stephen Meyer notes, the difference between ID and theistic evolution, as articulated by theistic evolutionists who are also scientists or philosophers of science, centers on an issue apart from the science:

Of the three reviewers, Wheaton College philosopher of science Robert Bishop was the least persuaded by DD‘s arguments — but, interestingly, he was also the most explicitly committed to the principle of methodological naturalism. Indeed, he objected to the thesis of the book precisely because it openly rejects (and violates) the principle of methodological naturalism.
Consequently, his four-part critique, by far the longest in the BioLogos series, said very little about my scientific arguments. (He did argue that I was wrong to claim that newer models of evolutionary theory represent significant deviations from neo-Darwinian orthodoxy. Yet, notably, biologist Darrel Falk’s review affirmed my assessment of these newer theories over and against Bishop’s.) In any case, Bishop focused his critique on what he called my "rhetorical strategies," giving particular attention to philosophical issues concerning the legitimacy of design inferences in biology.
In Bishop’s judgment, intelligent design flagrantly violates the rule of methodological naturalism — a rule that he regards as normative for the practice of all natural science because he believes (incorrectly, as it turns out) that "methodological naturalism is the way scientific investigation has been done since before the time of the Scientific Revolution." Indeed, as my colleague Paul Nelson pointed out in his response to Bishop’s critique, Bishop badly misreads the history of science. The design arguments developed by Isaac Newton — in the Opticks and the Principia, for instance �– alone contradict Bishop’s claims.

You sense that between the view of Stephen Meyer and Robert Bishop there is room for a fascinating and profound discussion — not so much about the science, though, as about philosophy. Meyer observes:

Unfortunately, methodological naturalism is a demanding doctrine. The rule does not say "try finding a materialistic cause but keep intelligent design in the mix of live possibilities, in light of what the evidence might show." Rather, MN tells you that you simply must posit a material or physical cause, whatever the evidence. One cannot discover evidence of the activity of a designing mind or intelligence at work in the history of life because the design hypothesis has been excluded from consideration, before considering the evidence, by the doctrine of methodological naturalism (and the definition of science that follows from it).
Nevertheless, having a philosophical rule dictate that one may not infer or posit certain types of causes, whatever the evidence, seems an exceedingly odd way for science to proceed. Scientists tend to be realists about the power of evidence, but skeptics about philosophical barriers — which, if it is anything, the rule of MN surely is. Placing the detection of intelligent design out of the reach of scientific investigation, before the evidence has had a chance to instruct us, looks like rigging a game before any players have taken the field.

Exactly. Still, an in-depth conversation between Meyer and Bishop would be something to watch. When it comes to religious folks who don’t know the science, it’s different. There the discussion tends to circle back on itself very quickly. In a blog for the Jerusalem Post, for example, writer R.P. Nettelhorst swings wildly:

I’ve disliked the Intelligent Design concept since I first heard about it several years ago. From the theological standpoint, I believe that the theory is deeply flawed. It is simply a new version of a very old error: the God of the Gaps fallacy. To put it simply, the God of the Gaps fallacy argues that God is to be defined as mystery. Where there is mystery, there is God: if we find something in the world we don’t understand, the explanation is always the same: God did it.
This is an incredibly lazy approach to the world.

"Lazy," you say? But obviously, as anyone knows who has followed the debate about ID, that’s not at all how intelligent design advocates argue, not remotely close. I tweeted to Nettelhorst, who teaches Bible at Quartz Hill School of Theology in Southern California, to ask how deeply he had studied the science behind ID, to allow him to judge it so harshly as science and as theology. The answer: Not too deeply. What books has he read by ID advocates?

All right, so he read a book several years ago. That probably puts him at an advantage compared to Rabbi Geoffrey A. Mitelman, of the group Sinai and Synapses.

Reactions to the fantastically popular Eric Metaxas article in the Wall Street Journal, arguing for intelligent design at the cosmological level, attracted criticism from Rabbi Mitelman, among others, writing at the Huffington Post. From his credentials, Rabbi Mitelman sounded like he must be a thoughtful guy. I tweeted with him too, and received a variety of comments on ID’s inadequacy as science.

See here for Casey Luskin on peer review and other signs that ID has the upper hand. As for not wanting to hear about ID from anyone associated with the intellectual hub of the ID movement, that would clearly handicap any scientific exploration he chose to do. But okay, I asked, how about physicist and Nobel laureate Charles Townes? No comment from Rabbi Mitelman.

What has he actually read on the subject?

If there was an answer on that, I missed it. I urged him to study up a bit, since the frontier of science and religion is advertised as his area of expertise. The best I could get from him was an agreement that informing himself, despite a priori objections, would do "no harm."

On ID as testable, falsifiable science, see here, here, and here for an introduction.

So there you have it. When they’re familiar with the science underlying the design inference, they give you philosophy. When they don’t know the science, they talk about the science, or simply make a hash of the two. Speaking of inferences, you can draw your own.

I’m on Twitter. Follow me @d_klinghoffer.

https://evolutionnews.org/2015/01/at_biologos_ste/

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Wednesday, November 26, 2014

Our Human Origins Continue to Remain Unclear. There have been several hominin species which all became extinct except our own - Homo Sapiens Sapiens

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Field work in Archaeology and Paleoanthropology is constantly turning up new evidence, which requires adjusting our theories about human origins, the appearance and extinction of species, and the migration of populations. Here are a number of fascinating links to explore.

https://www.nhm.ac.uk/discover/homo-erectus-our-ancient-ancestor.html

https://www.nhm.ac.uk/discover/human-evolution.html

https://www.nhm.ac.uk/discover/news/2021/february/modern-human-origins-cannot-be-traced-back-to-a-single-point.html

https://www.nhm.ac.uk/discover/news/2016/february/earliest-evidence-humans-breeding-neanderthals.html

https://www.nhm.ac.uk/discover/news/2018/january/humans-left-africa-40-000-years-earlier-than-we-thought.html

https://www.nhm.ac.uk/discover/news/2019/july/modern-humans-may-have-been-in-europe-150-000-years-earlier-than.html

https://www.nhm.ac.uk/discover/news/2021/february/modern-human-origins-cannot-be-traced-back-to-a-single-point.html

https://www.historymuseum.ca/neanderthal/

https://www.sciencemag.org/news/1996/12/early-human-species-may-have-coexisted-our-own

https://www.cmnh.org/pnas

NATURAL HISTORY MUSEUM

Human origins

http://www.nhm.ac.uk/nature-online/life/human-origins/early-human-family/index.html

1,800,000 – 200,000 BC Homo erectus

http://www.nhm.ac.uk/nature-online/life/human-origins/early-human-family/homo-erectus/index.html

900,000 - 700,000 BC Homo antecessor

http://www.nhm.ac.uk/nature-online/life/human-origins/early-human-family/homo-antecessor/index.html

600,000 - 250,000 BC Homo heidelbergensis

http://www.nhm.ac.uk/nature-online/life/human-origins/early-human-family/homo-heidelbergensis/index.html

400,000 – 125,000 BC Homo rhodesiensis

http://humanorigins.si.edu/evidence/human-fossils/fossils/kabwe-1

http://www.bradshawfoundation.com/origins/homo_rhodesiensis.php

400,000 - 35,000 BC Homo sapiens neanderthalensis

http://www.nhm.ac.uk/nature-online/life/human-origins/early-human-family/neanderthals/

http://archaeologyinfo.com/homo-neanderthalensis/

400,000 – present BC Homo sapiens sapiens

http://www.nhm.ac.uk/nature-online/species-of-the-day/evolution/homo-sapiens/

95,000 – 17,000 BC Homo florensiensis (The Hobbit)

http://www.nhm.ac.uk/nature-online/life/human-origins/early-human-family/homo-floresiensis/index.html

60,000 – 40,000 BC Denisovans

http://www.nhm.ac.uk/nature-online/life/human-origins/early-human-family/denisovans/index.html

Homo erectus Reconstruction of early Homo erectus

Homo erectus was the first of our relatives to have human-like body proportions, with shorter arms and longer legs relative to its torso.

H. erectus was also the first hominin known to have migrated out of Africa, and possibly the first to control fire and cook food.

Highly varied and by far the longest-lived of all the human species, H. erectus survived from about 1.8 million years ago in Africa and western Asia to possibly as late as 200,000 years ago in Indonesia.

Key fossils Replica fossil skull of 'Turkana Boy', a male Homo erectus aged 9-12 years old.

Although evidence suggests that H. erectus originated in Africa, the first fossils were found in Asia, and it is in Asia where this species survived for so long.

The first H. erectus fossil was found in Java, Indonesia in 1891, and is commonly known as Java Man. By 1940 many more remains had been found there, and in China.

However, the find that has revealed most about this species is ‘Turkana Boy’ from Nariokotome, Kenya. Unearthed in 1984, the skeleton is around 1.5 million years old and represents the most complete ancient human specimen ever discovered.

By studying his remains, scientists have concluded that H. erectus did not use trees for safety or as a food source like earlier hominins. Instead, they were a tall species that walked and ran in much the same way as we do.

Successful species?

In terms of species survival, H. erectus is a huge success story. Fossil evidence for H. erectus stretches over more than 1.5 million years, making it the longest surviving species of all our human relatives. Compare this to our own species, Homo sapiens, which has been around for perhaps 400,000 years so far, and we begin to appreciate the ability of this species to survive over a long period with many changes to the environment and climate.

Beyond Africa

Current evidence suggests all hominins before H. erectus lived in Africa. However, almost as soon as this species appears in the fossil record there is evidence it expanded out of Africa into western and eastern Asia and Indonesia.

Migration happens for many reasons but essentially H. erectus probably drifted across northern Africa, across the Sinai region into Asia, when suitable habitats and food sources stretched that far. Meat was an important part of their diet and carnivorous animals often range more widely than herbivores. This, together with their larger body size, helps explain the large geographic range of H. erectus.

Homo heidelbergensis Homo heidelbergensis reconstruction

Homo heidelbergensis is known to have lived from at least 600,000 years ago in Africa and Europe to maybe as late as 250,000 years ago in some areas.

They routinely butchered large animals, and their fossil remains are often associated with handaxes.

Evidence suggests that African H. heidelbergensis could be the ancestor of our own species, Homo sapiens.

Distinctly human

Replica of the Broken Hill skull from Kabwe, Zambia, the finest known example of Homo heidelbergensis

After 1 million years ago, we see different human species living across Asia and Europe as well as Africa, which are thought of as distinctly human in physique and behaviour. The first fossil identified as H. heidelbergensis was a jaw discovered near Heidelberg, Germany in 1907. Since then various other finds have been made in Europe, Asia and Africa. They show a less projecting face, more prominent nose and a bigger braincase than Homo erectus, but also more primitive features than those of Neanderthals and modern humans.

Some H. heidelbergensis individuals had brain sizes within the modern human range. However, facially they still looked very different from us, with a longer, lower shaped skull, large brow ridge and no chin.

Skilled and organised

Despite this illustration by Angus McBride, we are not sure whether Homo heidelbergensis actively hunted dangerous large animals, but they were certainly skilled at obtaining their meat.

Evidence shows that H. heidelbergensis was an accomplished tool-maker and skillfully butchered large animals. The remains of horses, elephants, deer and rhinoceroses with butchery marks on their bones have been found alongside fossils of this hominin in Southern England and Germany. Whether they actively hunted the animals isn’t known. But, even if they scavenged the carcasses, these hominins were organised enough to drive off dangerous competing animals such as lions, hyenas and wolves.

Common ancestor

Neanderthal and Homo sapiens DNA reveals that they shared a common ancestor about 400,000 years ago. Many scientists think this could have been H. heidelbergensis, giving rise to Neanderthals in Europe and to our species in Africa. And perhaps to the Denisovans in Asia.

Homo rhodesiensis Nickname: Rhodesian Man

Site: Kabwe, Zambia Date of discovery: 1921 Discovered by: Tom Zwiglaar
Age: Between 300,000 and 125,000 years old Species: Homo heidelbergensis

Searching for metal ore deposits in the limestone caves of Kabwe, Zambia, Swiss miner Tom Zwiglaar is credited with finding the first early human fossil ever to be discovered in Africa. When Kabwe (also known as Broken Hill) was sent to Arthur Smith Woodward, Woodward assigned the specimen to a new species: Homo rhodesiensis. Today, most scientists assign Kabwe to Homo heidelbergensis.

Kabwe shows features similar to H. erectus such as a low braincase profile (the area towards the back of the skull), large brow ridges, a slight widening of the midface known as the sagittal keel, and a protrusion at the back of the skull named the occipital torus. But Kabwe also resembles modern humans with a flatter, less prognathic face, and larger brain (1300 cubic centimeters).

This skull is one of the oldest known to have tooth cavities. They occur in 10 of the upper teeth. The individual may have died from an infection related to dental disease or from a chronic ear infection.

Image Credit: Jim Di Loreto and Don Hurlbert, Smithsonian Institution

Bradshaw Foundation

Homo rhodesiensis is an extinct hominin species living between 400,000 and 125,000 years ago. It is known as 'Rhodesian man'. The fossil Kabwe skull is the type specimen of this species, found at Broken Hill in Northern Rhodesia, now Zambia, by Tom Zwiglaar in 1921.

Homo rhodesiensis was robust, with very large brow ridges and broad face. It is also referred to as 'African Neanderthal', although it demonstrates intermediate features between Homo sapiens and Homo neanderthalensis, with a close association to Homo heidelbergensis. It has been argued that it was the ancestor of Homo sapiens idaltu - 'Herto Man' - which itself was the ancestor of Homo sapiens sapiens.

Neanderthals (Homo neanderthalensis)

http://www.nature.com/news/modern-human-genomes-reveal-our-inner-neanderthal-1.14615

Neanderthals began to evolve about 400,000 years ago, and survived in Europe and Asia until around 35,000 years ago. Meanwhile modern humans (Homo sapiens) were evolving in Africa. Thanks to an abundance of fossil evidence, we have a good idea of what Neanderthals probably looked like. The animation above shows a typical Neanderthal man. His large nose and strong

double-arched brow ridge distinguish him from a modern human.

Who were the Neanderthals?

Illustration of a Neanderthal woman. © John Sibbick / Natural History Museum

Hundreds of Neanderthal fossils have been found since the first identified in 1856 in the Neander Valley, Germany, allowing us to build up an almost complete picture of a typical Neanderthal body.

They had large brains and short, stocky physiques suited to living in cold environments. Their big nose was also adapted to warming and humidifying the air.

Neanderthals were skilled hunter-gatherers, made and used flint and stone tools, built shelters and controlled fire. They were highly carnivorous but they also ate other foods, although only limited evidence of plant foods survives in the archaeological record. In Mediterranean regions the Neanderthals exploited marine resources such as shellfish and seals, but their use of aquatic foods was certainly more limited than that of modern humans.

Neanderthals behaved strikingly like our own species in some ways. As well as making and wearing clothes and probably also simple jewellery, archaeological evidence also suggests that they buried their dead.

A close relative

Neanderthal burial site at Kebara, Israel. Some scientists believe that such sites suggest that Neanderthals honoured their dead.

Fossil and genetic data suggest that Neanderthals shared a common ancestor with our species around 400,000 years ago, thought by many scientists to be Homo heidelbergensis.

In 2010, most of the Neanderthal genome was mapped and compared to modern populations of Homo sapiens, revealing that the Neanderthals' relationship to some modern humans was even closer than previously thought. The results showed that people in Europe, Asia and New Guinea have around 2.5% Neanderthal DNA in their genetic code, suggesting Neanderthals interbred with modern humans not long after they spread out of Africa.

Why did the Neanderthals die out?

All physical evidence of the Neanderthals disappears around 30,000 years ago. Modern humans reached Europe around 15,000 years earlier and it has been suggested that superior brains, language and skills allowed them to prevail over the Neanderthals. However, this may underestimate our relative.

An alternative view suggests that Ice Age climate fluctuations affected European flora and fauna, causing the disappearance of familiar plants and animals, and that modern humans were better able to adapt than Neanderthals.

Homo sapiens

Carolus Linnaeus © Wikimedia

Taxonomy Homo sapiens

Empire     Eukaryota
                Kingdom     Animalia
                                Phylum       Chordata
                                                Class     Mammalia
                                                                Order     Primates
                                                                                Family     Hominidae
                                                                                                Genus     Homo
                                                                                                                Species       sapiens

Homo sapiens is the most widely dispersed and numerous medium-large size mammal, and the only extant member of the genus Homo.

The type specimen of Homo sapiens is Carl Linnaeus (1707–1778), based on the descriptions in the 10th edition of his Systema Naturae (Linnaeus, 1758).

No single person was recognised as the type specimen until 1959, when William Stearn wrote that "Linnaeus himself, must stand as the type of his Homo sapiens". This was enough to designate Linnaeus as a lectotype - the single name-bearing type specimen for the species Homo sapiens.

Genus characteristics include a high degree of encephalisation and a skeleton adapted to habitual bipedalism. Species traits include:

a globular cranial vault
supraorbital ridges small or absent
a chin on the lower jaw

The origins of humankind on Earth

It is estimated that the first members of the human family (hominins) lived in Africa about 6 or 7 million years ago. They are believed to have been forest-dwelling, perhaps walking upright in the trees or when on the ground.

In 2001, cranial fossils of Sahelanthropus tchadensis dating to this time were uncovered in Chad, central Africa. The fossils show a combination of ape-like and human-like features, although how closely related Sahelanthropus tchadensis is to humans is the subject of debate.

Over millions of years, distinct species and lineages emerged and radiated across Africa. Among them were the earliest members of the genus Homo, to which modern humans belong.

Replicas of the remarkably complete Australopithecus sediba fossil skeletons found in Malapa Cave, South Africa in 2010.

The earliest fossil evidence of these ancient humans dates to between 1.9 and 2.4 million years ago, and comes from East Africa, although a human-like form of the species Australopithecus has recently been described from South Africa. Australopithecus sediba is 1.98 million years old and is the most human-like australopithecine yet discovered, with an increased front brain cavity and small teeth.

The emergence of modern humans

Fossil evidence suggests that modern humans evolved in East Africa around 200,000 years ago, since fossils more than 150,000 years old are known from Ethiopia and Kenya. However, genetic data from recent African populations suggests that other regions may also have been important.

One study compared the DNA of modern hunter-gatherers. The results revealed that Namibian and Khomani Bushmen of southern Africa, Biaka Pygmies of Central Africa and the Sandawe of East Africa have the highest levels of genetic diversity in the world for the DNA studied.

Although genetic studies should be treated with caution when it comes to pinpointing origins, genetic diversity is one indicator of how ancient a people are. In principle the more ancient the population, the more time it has had to build up diversity.

Distribution

Human diversity

Humans occupy most terrestrial environments and are the most abundant medium-sized mammal on earth. Putative early members of the species lineage are known from Africa at more than 250,000 years ago, while examples showing the modern anatomical pattern date from 195,000–100,000 years ago in Africa, and 90,000–120,000 years ago in the Middle East.

The earliest well-dated diagnostic Homo sapiens fossils in Europe, eastern Asia and Australasia date from 40,000–45,000 years, and in the Americas from less than 15,000 years.

Biology

Vitruvian man by Leonardo da Vinci

Morphology

Humans can be distinguished from other living apes by a strikingly enlarged brain, reduced hair coverage on most parts of the body, and by a suite of skeletal and muscular adaptations associated with habitual bipedal locomotion, including the loss of the grasping ability of the foot. Humans are terrestrial bipeds with a limited ability to swim and dive that must be learned.

The species shows strong variation in body size and proportions, and pigmentation, some of which can be related to the wide range of environments in which Homo sapiens lives. Humans exhibit moderate sexual dimorphism in body size.

Nutrition

Humans are opportunistic omnivores, showing remarkable ingenuity in extracting, producing, processing and preserving foods. Humans are the only species that can control or make fire, and cooking is practiced by all known extant human groups.

Regional variations in diet are influenced by availability within a particular environment, by cultural traditions such as food preferences and avoidances, and even genetic factors. Lactase persistence, which allows some people to consume milk and dairy products throughout life, is a recent adaptation to dairy consumption that would only have been useful among populations with a tradition of dairy farming.

Life cycle

Human social structure is highly variable. Traditional arrangements that may be formalised through marriage include monogamous pairs as well as one-male multi female groups and, more rarely, one-female multi-male groups.

Both males and females may disperse from their natal community. Human infants are born in a relatively immature state and remain dependent on adult carers for several years.

Inter birth intervals are relatively short such that females may have multiple dependent offspring at different stages of developmental maturity. Other members of a community or extended family network may contribute to the care of dependent children, including fathers, older siblings and grandparents.

Humans are typically diurnal and sleep in temporary or permanent shelters at night. Family groups often have exclusive use of a shared sleeping space or residence that may serve as a home base for extensive periods.

Behaviour

A shell bead from Skhul Cave in Israel, dated to 100,000 years ago.

The beginnings of modern human cultural complexity can be traced back at least 100,000 years in Africa and the Middle East. African sites have extensive evidence of the use of red iron oxide pigments, for colouring shell beads and (probably also) the human body, while in the Middle East there are cave sites in Israel with shell beads (one is pictured from the site of Skhul), pigments, and human burials with associated grave goods such as deer antlers.

This species is a large-brained biped, tool-making and tool-using, with an ancestral hunter-gatherer lifestyle, now extended to pastoralism, agriculture and industrialised urbanism.

Behaviour includes complex treatment of the dead, and symbolism including:

representational art
music
religious beliefs
complex language
complex social systems

Conservation

· Human activities, associated with a rapidly increasing demand for food, timber, fibre, and fuel have profoundly affected the ecosystems on which humans and other species depend for their well-being.

· In the past century the scale and complexity of human activity has increased to the point where human activities are threatening other species and also affecting our own wellbeing as a result of environmental degradation and the likelihood of humanly-induced global warming.

Homo floresiensis (the 'hobbit')

Model of the skull of Homo floresiensis, the small, human-like species nicknamed ‘the hobbit’.

In 2003, archaeologists on the island of Flores, Indonesia, made what has proved to be an extraordinary find. They unearthed the skeleton of a 1m-tall individual, nicknamed ‘the hobbit’, with some human-like features yet a small, chimpanzee-sized brain. Analysis revealed it to be just 18,000 years old. This new human species was named Homo floresiensis and since its discovery other fossils have been found that suggest this strange hominin lived between 95,000 to as late as 17,000 years ago.

Why was the hobbit so small?

Due to its diminutive stature, the first H. floresiensis specimen unearthed is thought by some scientists to be a diseased modern human. However, multiple fossils with similar features have since been found.

Instead, it appears the hobbit may be an example of ‘island dwarfing’ – an evolutionary response that occurs when populations of large mammals become isolated on an island with a limited food supply and a lack of predators.

A contradiction

H. floresiensis is a puzzling species. The very small brain size, short legs, ape-like wrists and hipbone suggest it is more like an australopithecine (a group living over 2 million years ago) than a human. However, other parts of its anatomy suggest that it is a human species.

Archaeological evidence found in the same cave on Flores indicates H. floresiensis may have used tools and even hunted and controlled fire. Were their small brains somehow reorganised to allow for more human-like behaviour? Or were early modern humans responsible for some of this archaeological evidence?

Yet more questions

The discovery of H. floresiensis has raised many questions - not only about this species, but about the human fossil record in Asia as a whole. Stone tools dating back over 800,000 years have been found on Flores, but we have no other evidence on the island of human evolution between this time and the time of H. floresiensis.

Is this species a descendant of Homo erectus, who migrated out of Africa into Asia? How did their ancestors reach the island of Flores? Only modern humans are thought to make boats to purposely cross stretches of water.

Did H. floresiensis and our species, Homo sapiens, ever come into contact with one another? And what happened to H. floresiensis? Was a volcanic eruption on the island the reason they became extinct?

The discovery of this species highlights how much still remains to be learnt about human evolution in Asia.

Denisovans

Molar tooth belonging to a Denisovan, thought to be a new branch of ancient humans that overlapped in time with Neanderthals and modern humans. © MPI-EVA, Leipzig

Denisovans, together with Neanderthals, are our closest extinct relatives. They are a recently discovered group of ancient humans from whom only a few fossil fragments, dated to about 40,000 years ago, have been found.

Not only did this group exist at the same time as modern humans, remarkable genetic research has revealed that they interbred with some populations.

DNA evidence provides clues

In 2010, scientists analysed limited DNA from a fossilised finger and a molar tooth unearthed in Denisova Cave in the Altai Mountains, Siberia. The initial research suggested they were from a genetically distinct group of ancient humans that shared a common ancestor with modern humans (Homo sapiens) and Neanderthals (Homo neanderthalensis) about 1 million years ago. However, the whole Denisovan genome has now been reconstructed and indicates a closer link to the Neanderthals.

Just as remarkable was the discovery that the Denisovans, as this ancient human group has become known, are related to a particular group of humans alive today – Australasians, who live on some of the islands north of Australia and in Australia itself.

Evidence of interbreeding

The study showed that Australasians share around 5% of their genetic material with the Denisovans. The most plausible explanation is that Denisovans were present further south as well as in Siberia, and that they encountered and interbred with pre-Australasian populations of modern humans migrating from Africa though south east Asia around 60,000 years ago.

If the populations were very small, it wouldn’t take much interbreeding to make a genetic mark. As few as 50 Denisovans interbreeding with 1,000 pre-Australasians could result in their present-day descendants sharing 5% of their genetic material with Denisovans.

Human evolution in Asia

Genetic information suggests that Denisovans may have been part of the Homo heidelbergensis lineage. In Europe, Homo heidelbergensis gave rise to Neanderthals, in Africa they gave rise to us (modern humans), and in Asia, perhaps to the Denisovans.

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Monday, January 19, 2015