Author: Simon Brown

09 November 2017: the eighth great ape and the problem with ‘species’

Until recently, only seven species made up the group of primates known as the great apes, or Hominidae. Two orangutan species (Sumatran and Bornean), two gorilla species (eastern and western), two chimpanzee species (chimpanzees and bonobos), and us.

But in a report recently published in Current Biology, an international team of scientists announced a new hominid with fewer than 800 members, Pongo tapanuliensis, found just south of Lake Toba in Sumatra. To save your tongue twisting around that particular binomen, we can call it the Tapanuli orangutan.

The scientists compared skull, jaw and dental characteristics of a Tapanuli specimen with those of the Sumatran and Bornean species, and analysed 37 orangutan genomes as a second line of evidence.

Orangutan

Three species of orangutan: from left, Bornean, Sumatran, Tapanuli. Photo credits: Eric Kilby, Aiwok, Tim Laman

The report gained a great deal of media attention: not only because we humans had a new cousin, but because the Tapanuli is an endangered species.

However, there were dissenting voices. In an interview with the ABC, for example, Lee Christidis from Southern Cross University pointed out that the analysis had been carried out on only one specimen and that the DNA evidence was at best ambiguous.

It’s only fair to point out that it’s often the case that a species will be described by a single representative organism, or, as happens frequently in palaeontology, those fragments of a single organism that have been fossilised or otherwise survived over many millions of years.

The report also generated discussion about what we mean by the word ‘species’. Jerry Coyne, professor emeritus at the University of Chicago and author of the excellent Why Evolution is True, wrote in his blog:

‘Not only do I see this new “species” as merely an isolated and genetically differentiated population (as are many human populations regarded as H. sapiens), but I’d also contend that there is only one species of orangutan overall, with these three groups all being subspecies. Sadly, a lot of systematists don’t see it that way, as they seem to think that any isolated population, if it can be told apart morphologically or genetically from others, warrants being named as a new species. Yet to evolutionists, a “species” is not an arbitrary segment of nature’s continuum, but real entities that maintain their “realness” because they don’t exchange any (or many) genes with other such entities where they cohabit in nature.’

But is this indeed the definition of species with the greatest currency among most biologists?

To start with, there has to a definition that works across all fields. A primatologist cannot have a different concept of species from, say, an entomologist, or the whole point of taxonomy – the orderly classification of living things that demonstrates their evolutionary relationships – starts to fall apart.

This doesn’t mean that definitions in biology – or any scientific endeavour, for that matter – are written in stone. As our knowledge of the world around us grows, the language we use to explore, explicate and explain that knowledge must also grow.

The definition I was taught at school is not dissimilar to Coyne’s quoted above, and is based on what is called the Biological Species Concept (BSC), developed by Ernst Mayr and Theodosius Dobzhansky in the early 1960s (Coyne did some graduate work under Dobzhansky at Rockefeller University). As Colin Groves, professor emeritus at the Australian National University, wrote, ‘This concept states that under natural conditions a species ‘should not exchange genes with other species’[i]. Groves goes on to point out that ‘ … the popular idea that two species are “unable” to interbreed is  a misunderstanding: it is not that they cannot interbreed, it is that they do not.‘

The BSC was further refined by Mayr and Jared Diamond in a paper on Melanesian birds in 2001, and then in 2004 by the aforementioned Jerry Coyne with H. Allen Orr in a book about speciation called, appropriately enough, Speciation.

Groves argues that the modified definition of BSC risks different standards of comparison in different taxonomic groups: it’s a definition that won’t work across different fields, in other words.

Groves again: ‘If a genus contains a pair of sympatric[ii] sibling species (species that differ only slightly, inconspicuously), the standard for species recognition will be set much “lower” than in a genus in which sympatric species pairs are grossly different. It is the search for objective standards – for an operational means of distinguishing species – that has been responsible for the controversies that marked taxonomic discussions over the past 15 or 20 years.’[iii]Taxonomy

Many biologists now use what is called the Phylogenetic Species Concept (PSC), developed by American biologist Joel Cracraft from the early 1980s. Put very simply, in this concept a species is the smallest population of organisms that is measurably different from other populations sharing the same ancestry. Note that this concept says nothing whatsoever about species sharing genes, such as happened between Homo sapiens and H. neanderthalensis around 100,000 years ago.

It’s important to note that both the BSC and the PSC are attempts to operationalise the evolutionary concept of species; that is, that a species is an evolutionary lineage.

While the report in Current Biology describing the Tapanuli orangutan as a new species of great ape has, for the most part, been received positively, the fact that many distinguished scientists question the findings shows that the debate about what constitutes a species is ongoing.

[i] Groves, Colin. ‘Speciation in hominin evolution’; African Genesis: Perspectives on Hominin Evolution; ed Reynolds, Sally C. & Gallagher, Andrew; Cambridge University Press; Cambridge; 2012, p 46.

[ii] Sympatry occurs when two or more species live in the same geographic area.

[iii] Ibid.

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07 November 2017: Dreaming in the Dark anthology wins World Fantasy Award

For the second time, one of Jack Dann’s Dreaming anthologies has won a World Fantasy Award.

dreaming-in-the-dark-hardcover-edited-by-jack-dann-4112-p[ekm]298x420[ekm]

Dreaming in the Dark, ed Jack Dann, PS Publishing

Last night, Dreaming in the Dark, edited by Jack and published by PS Publishing, won the 2017 World Fantasy Award for Best Anthology.

In 1999, the first in the series, Dreaming Down-Under, edited by Jack and his partner Janeen Webb, won the same award.

I was fortunate enough to have stories included in both.

That the anthologies should receive such an honour says a great deal about Jack’s dedication to Australian writers of speculative fiction. We all owe him a great debt.

Congratulations, Jack!

17 October 2017: Walking statues, colonialism and free speech

I am a white male living in a society largely designed by white males for the benefit of white males. As such, I am a member of history’s most privileged group, a group that numbers no more than a few hundred million in a world inhabited by over seven billion human beings.

What got me here, together with every other member of that group, was a toxic mixture of imperialism and colonialism. Not toxic for me, I hasten to point out, but toxic for billions of other human beings.

It’s not necessary to point out how many first peoples suffered because of European expansion from the 15th through to the 20th centuries. Nor should we defend that expansion by referring to the benefits brought by the introduction of ‘Western’ inventions such as double-entry bookkeeping and modern farming methods, as if they were handed out by the Conquistadors and Australia’s first settlers at the same time as the distribution of smallpox and musket balls.Imperialism

Imperialism and colonialism also transformed slavery into a global business. The fact that Europeans didn’t invent slavery shouldn’t stop us acknowledging that developments such as double-entry bookkeeping helped Europeans perfect it, in the same way the musket ball helped perfect total war.

In a very roundabout way that brings me to the topic of walking statues. Specifically, Rapa Nui’s moai – the monumental statues of Easter Island.

Rapa Nui has been used as the example par excellence of ‘ecocide’, what happens to a society that selfishly exploits its own environment beyond recovery and thereby destroys itself. I swallowed without questioning this explanation for the island’s depopulation and deforestation, promoted in books like Jared Diamond’s Collapse: How Societies Choose to Fail or Survive.

But it may not be true.

University of Bristol researcher Catrine Jarman explains in her article in The Conversation, that many decades of archaeological research on Rapa Nui ‘paints a very different picture’.

As Jarman writes:

‘The ecocide hypothesis centres on two major claims. First, that the island’s population was reduced from several tens of thousands in its heyday, to a diminutive 1,500-3,000 when Europeans first arrived in the early 18th century.

‘Second, that the palm trees that once covered the island were callously cut down by the Rapa Nui population to move statues. With no trees to anchor the soil, fertile land eroded away resulting in poor crop yields, while a lack of wood meant islanders couldn’t build canoes to access fish or move statues. This led to internecine warfare and, ultimately, cannibalism.’

Essentially, there is no convincing evidence that Rapa Nui’s population declined before first European contact in 1722. Furthermore, recent evidence suggests that the island’s population successfully sustained itself for centuries despite deforestation occurring soon after the island’s initial settlement by humans, deforestation caused by the accidental introduction of the Polynesian rat which ate palm nuts and saplings.

So what did happen to the people of Rapa Nui?

Again, in Jarman’s own words:

‘Throughout the 19th century, South American slave raids took away as much as half of the native population. By 1877, the Rapanui numbered just 111. Introduced disease, destruction of property and enforced migration by European traders further decimated the natives and lead to increased conflict among those remaining.’

The disaster that befell the people of Rapa Nui came about because of the slave trade of the 18th and 19th centuries, itself a result of European imperialism and colonialism. Effectively, the victims of that depopulation subsequently were found guilty of the crime.

If the forests weren’t cut down to move the moai, how did the islanders transport the statues from where they were made to where they were eventually sited?

Moai

Rapa Nui moai

It turns out they probably moved them in the same way you or I would move a heavy washing machine or refrigerator … they walked them. Admittedly, this involved a great deal more human muscle power and coordination than two people clumsily angling white goods through a narrow corridor. Recent experiments show that this was perfectly possible.

(For a full explanation of how this was done, and the true story of how Rapa Nui became depopulated, check out The Statues that Walked, by Terry Hunt and Carl Lipo.)

I can’t argue that imperialism and colonialism had no benefits. It benefitted me, for example. Without them I wouldn’t be here now, a middle-aged male living in middle-class splendour in Australia, a collection of ex-colonies. Nor can I argue against the proposal that the modern world is a direct result of those movements. Nor can I argue against the proposal that industrialisation and modernisation, two direct products of those movements, hasn’t improved the lot of billions of human beings over the last two centuries.

What I can’t argue, however, is what Portland State University’s Bruce Gilley suggests in an article recently published in Third World Quarterly. An associate professor of political science, Gilley proposes that ex-colonies that develop their Western colonial legacy do better that those that reject that legacy. One of the examples he uses is the modern nation of Singapore.

I suspect Gilley is wrong, especially in the case of Singapore where its success is almost entirely due to the self-created ‘Singapore model’, a mixture of democracy, authoritarianism and meritocracy that has delivered remarkable growth and one of the world’s highest standards of living. But I strongly believe Gilley has every right to express his academic opinion in an academic journal.

Singapore

Singapore skyline

As reported by Andy Ngo in Quillette, both Gilley and the journal’s editor-in-chief Shahid Qadir received threats of violence after the appearance of the article on 8 September, and the publishers of Third World Quarterly have withdrawn it. I recommend reading Ngo’s piece to get the full story.

I do not think hate speech or speech inciting violence should ever be published, whether it is an article written for a journal, an opinion piece in a newspaper, or an enraged Tweet by an American president. But I do not think it is right to censure someone’s research because you disagree with its conclusion. In fact, that kind of thinking encourages hate speech and incites violence. Worse, ultimately, it shuts off debate, dialogue and intellectual curiosity.

The problem for those who think that the evils of colonialism are so great that any defence of it is anathema and should be closed down is simply this: it allows history to be written by those who shout the loudest. It establishes a precedent, a precedent that may one day lead to the censorship of articles that explain why colonialism was wrong, and how the moai of Rapa Nui came to walk.

(NB Jared Diamond has responded to some of the claims made in Hunt and Lipo’s book, The Statues that Walked. You can check that out here. Thanks to friend, physicist and fellow-writer Rob Porteous for the heads-up.)

07 October 2017: New evidence suggest we are much older than 300,000 years

In a recent blog I wrote about new dates for skulls found in the cave of Jebel Irhoud in Morocco in the 1960s. Originally assessed as belonging to Homo neanderthalensis (an assessment that was soon challenged), a reappraisal published in Nature this year confirmed they were in fact H. sapiens skulls; the great surprise was that the reappraisal determined them to be at least 300,000 years old.

Jebel Irhoud

Cast of Jebel Irhoud 1 from the Australian National University. Photo: Simon Brown

New work done by scientists in Sweden and South Africa, and reported in Science, have now dated DNA obtained from a 2000-year-old Khoe-San skeleton apparently unmixed with Bantu or Eurasian DNA, as having separated from other H. sapiens sometime between 260,000 and 350,000 years ago.

The San are the First People of South Africa, Botswana and Namibia. Indeed, they may be the First People, the ancestral group all modern humans are descended from, or at the very least very closely related to them.

The San are the most genetically diverse of all humans living today. In an episode of Catalyst on the ABC about her research on San DNA, Professor Vanessa Hayes said, ‘There’s more similarity between myself and a Han Chinese than between two San people.’

Bushman

San hunter/gatherer

As reported in Science, the recent work on San DNA involved several ancient individuals, but the standout dates were given by DNA from the genome of a hunter-gatherer boy known as Ballito Bay A. The scientists concluded that, ‘ … our results show that the deepest split among modern humans (the estimated latest time for the emergence of H. sapiens) occurred at between 350 kya and 260 kya.’

Given that the skulls found in Morocco have been dated to at least 300,000 years ago, it would seem not unreasonable to consider the older dates for the emergence of H. sapiens – 350,000 years ago – being closer to the mark than the lower date of 260,000 years ago.

This new evidence also adds weight to the theory that our species may have partly evolved in South Africa.

In the last eight months, we have seen conservative estimates for the age of our species jump from 190,000 years old to almost double that. It’s been an extraordinary year for palaeoanthropology.

29 September 2017: What ancient hominid left her footprints in Crete?

There is strong evidence that a hominid walked in Crete in the late Miocene, about 5.7 million years ago.

In an article in the 31 August 2017 issue of the Proceedings of the Geologists’ Association, the authors describe the discovery in western Crete of tracks in rock accurately dated to the Messinian age. To quote the abstract, ‘The tracks indicate that the trackmaker lacked claws, and was bipedal, plantigrade, pentadactyl and strongly entaxonic.’

Trachilos footprints Andrzej Boczarowski

Ancient hominid footprints near Trachilos, Crete. Photo: Andrzej Boczarowski

In plain English, the authors are describing footprints impressed in rock that suggest the creature that made them walked on two feet, not four (bipedal), that it walked on its whole foot rather than just on its toes or claws (plantigrade), that it had five digits on each limb (pentadactyl), and that its big toe was bigger than its other toes (entaxonic).

In short, a footprint that resembles those that are left behind by hominins – the family of humans that includes you and me.

The paper caused a small storm in palaeoanthrapological circles for two reasons. First, there is little direct evidence anywhere of bipedalism before the Pliocene (the epoch immediately following the Miocene, starting around five million years ago), and second, there was no evidence of bipedalism outside of Africa before the Pliocene.

If the tracks discovered in Crete have been accurately dated, and the evidence seems strong on this point, then several intriguing possibilities present themselves.

First, that bipedalism, as palaeoanthrapological orthodoxy has it, evolved in Africa in a species that subsequently migrated to Eurasia (or possibly one of that species’ close descendants made the journey) much earlier than first believed.

Second, that bipedalism in our family may have evolved in Eurasia and not Africa.

Third, that bipedalism evolved more than once in our family. This would make it an extraordinary example of convergent evolution.

At this point, without completely discounting it, the first possibility seems the most unlikely, simply because there is no evidence – fossil or footprint – to support it. However, if this turns out to be the correct answer, a prime candidate would have to be Orrorin tugenensis, the oldest hominid for which we have strong evidence for bipedalism. Orrorin lived in Kenya in the late Miocene, so the dates fit.

The second possibility has been championed by scientists who think it may have been left by Graecopithecus freybergi, a hominin known by one mandible and a few teeth discovered in Greece. Although we do not know if Graecopithecus was bipedal, a recent paper proposed that its dental morphology suggests it is the oldest hominin and that therefore humans first appeared in Eurasia and not Africa.

Graecopithecus_tooth

Teeth from Graecopithecus freybergi

While this claim has been controversial, if Graecopithecus was the first hominin then it was almost certainly bipedal and may well have left impressions of its footprints in Crete. However, generally speaking dentition follows diet. Our teeth can evolve quickly to take advantage of new resources in food, so it is possible that despite its human-like teeth Graecopithecus was a hominid (a member of the family that include great apes as well as humans) but not specifically a member of the tribe Hominini. If this is the case, then Graecopithecus is only our distant cousin rather than an ancestor.

This leads to the third possibility, that bipedalism evolved more than once in the hominid clade. If this is the case, then there is one other strong Eurasian candidate for the owner of those footprints left behind in Miocene Crete, and some scientists think this candidate may have been bipedal.

Oreopithecus bambolii is known from 9-7-million-year-old fossils discovered in Italy from the 1870s. The best and most complete fossil was found in lignite, earning it the name of the Abominable Coalman.

For a long time the position of Oreopithecus in the hominid record has been controversial, most disagreement revolving around whether it is part of the ape or the human family.

Oreopithecus

Oreopithecus bambolii – the ‘Abominable Coalman’

Work done on Oreopithecus in the 1990s controversially proposed it was bipedal, although with a curiously positioned big toe that meant its foot may have acted almost like a tripod. This suggests it could walk on two feet, but probably not at any great pace.

A recent survey of the hominid’s spine, however, has led some scientists to think Oreopithecus was not fully bipedal. Furthermore, the footprints in Crete do indicate a more conventionally shaped foot.

The tracks were discovered in Crete, and dated to the Messinian age when the sea level of the Mediterranean was probably similar to now. Graecopithecus somehow would have had to make it across the equivalent of the Aegean Sea to reach Crete, and Oreopithecus across the Ionian and Aegean seas. Orrorin would have had to make it all the way from Africa. Of course, many animals throughout history have crossed seas and even oceans to reach isolated islands, including members of the hominid clade (Homo erectus to Java and Homo floresiensis to Flores, for example), but to date there is no fossil evidence of either Graecopithecus or Oreopithecus having lived – let alone walked – on Crete.

(This blog entry is based on an idea proposed by Colin Groves, Emeritus Professor of Bioanthropology at the Australian National University.)

15 July 2017: New dates for Homo naledi and (surprise!) new dates for H. sapiens

I originally intended to write about how recent dates discovered for Homo naledi meant that it and H. sapiens, our own species, had only the narrowest window in time to cross paths, but recent finds in Morocco have put paid to that. The announcements of the two sets of dates occurred within days of each other, and demonstrate just how quickly our knowledge of early human evolution is itself evolving.

Homo_naledi_holotype_specimen_(DH1)

Holotype specimen of H. naledi (Photo: Lee Roger Berger research team)

The new information for H. naledi appeared in three papers published in eLife (here, here and here) in May 2017, and provided more detail about when this newly discovered species walked the Earth, as well as announcing the discovery of a second area – the Lesedi Chamber in the Rising Star cave system about 50 km northwest of Johannesburg in South Africa – containing yet more H. naledi remains.

(For more on the first discovery, see in an earlier blog the interview I did with Elen Feuerriegel, one of the ‘underground astronauts’ involved in the recovery of the H. naledi remains in the Dinaledi Chamber).

Morphologically, the new species contained features that positioned it somewhere between the Australopithecines and the early members of our own genus, Homo; this would place it somewhere around two million years old. Confusingly, however, the bones found in the Dinaledi Chamber were still made up of hydroxylapatite, a form of calcium that takes up around 70% of the weight of human bones. Normally, fossilization results in the hydroxylapatite being replaced by minerals like silica. This suggested a more recent existence for H. naledi.

And the bones spoke true. The new papers give dates for the remains that placed it between 335,000 and 236,000 years old. Since the conservative dates for our own species up to May were 190,000 years ago, or 260,000 if you count the Florisbad skull as belonging to our own species instead of another such as H. heidelbergensis, it seemed unlikely, if remotely possible, that our ancestors crossed path with H. naledi.

But then came the second announcement.

A paper published in Nature in June 2017 revealed that H. sapiens remains discovered at a cave called Jebel Irhoud in Morocco, approximately 100km west of Marrakesh, and retrieved largely during the 1960s, have now been dated to extend as far back as 300,000 years, pushing it way beyond Florisbad and well within reach of H. naledi.

Jebel_Irhoud_1._Homo_Sapiens

Irhoud 1(Photo: Ryan Somma)

The skulls among these finds are not shaped like modern human skulls; the remains were originally classified as belonging to a sort of African Neanderthal. But the faces are flat, like our own, without the prominent inflated brow ridge of Neanderthal.

Where exactly they lie in the long line of human evolution is not known for certain, but their location and their age suggest strongly that they are archaic H. sapiens and not some other species.

While this does not change the overall pattern of human evolution as currently understood, it does dramatically extend the time that our species has existed, and strengthens the argument that the cradle of modern humanity was indeed Africa.

14 May 2017: New story out in Review of Australian Fiction

Very pleased to announce a story written with the amazing Anna Tambour, titled ‘Joy’, has appeared in the Review of Australian Fiction.RAF

What’s more, it appears in the same issue as ‘Water Cools Not Love’, a story by another wonderful writer, Laura Goodin.

The issue can be found here.