Anthropology.net

“Hominin – the group consisting of modern humans, extinct human species and all our immediate ancestors (including members of the genera Homo, Australopithecus, Paranthropus and Ardipithecus).”

Australian Museum.

A lot had happened this year with hominin research and some would redefine conventional understandings of this group. Below is a list of new studies that came out this year that I find quite interesting on hominin. Read up so you can show off in class with your knowledge of current hominin research. You know, just so you can make sure that your adjunct is really paying attention of what he/she is doing instead of begrudgingly teaching a class because he/she has to. Or maybe you have a geeky classmate you want to impress. Or if you’re like me, you just wanna be the smartest in class because Asian Fail is not an option. So, enjoy … and if they question you, tell them I said so.

Australopithecus africanus and Paranthropus robustus

• Male philopatry and female dispersal in both A. africanus and P. robustus. Is this a strategy to prevent inbreeding and mate choice by females? Ancient Hominid Males Stayed Home While Females Roamed, Study Finds

Paranthropus boisei

• Seems like we’ll have to re-evaluate P. boisei‘s nickname, “Nutcracker Man”. Recent study showed that P. boisei didn’t eat nuts but instead used its big teeth to chew on grasses and sedges. No nuts for ‘Nutcracker Man’: Early human relative apparently chewed grass instead

Homo erectus

• H. erectus were the first to controlled fire but it wasn’t just used for warmth. New study shows that H. erectus were the first to cook their food (with fire) and process their food with tools. Homo Erectus Processed Food Like Humans, Harvard Scientists Say

• Stone artifacts, mostly flakes from stone tools, from the Dmanisi site in Georgia (the country, not the state) might suggests that H. erectus evolved outside of Africa. However, no conclusive evidence can be made due to the poor conditions of fossils found near these artifacts. Human ancestors in Eurasia earlier than thought

• H. erectus reached South Asia earlier than previously thought, between 1.5 to 1 million years ago according to Acheulean tools. Go east, ancient tool makers

• Findings from Solo River Terrace (SoRT) in Indonesia shows that H. erectus never coexisted with H. sapiens. Using three dating techniques: U-series, Electron Spin Resonance (ESR) and argon-argon, scientists found H. erectus went extinct between 143,000 to 550,000 years ago. H. sapiens are thought to reached Indonesia about 40,000 years ago. Human Ancestor Older Than Previously Thought; Finding Offers New Insights Into Evolution

Homo neanderthalensis

• Neandertals probably died off because there were too many early humans to compete with. According to a statistical analysis, the Périgord region of southwestern France has the highest concentration of Neandertals and early humans. The ratio between Neandertal to early human was 1 to 10. There were just too many humans for Neanderthals to survive

• Mousterian culture might have lasted longer than previously thought and Neandertals might have spread as far as northern Russia in the mountains of Polar Urals, near the Arctic Circle. Last Neanderthals Near the Arctic Circle?

• Neandertals were predominantly right-handed, according to their teeth. Also, humans have been predominantly right-handed for at least 500,000 years. Neanderthal ancestors were mostly right-handed

Homo floresiensis (the Hobbits)

• The debate whether H. floresiensis is a separate species or just microcephalic H. sapiens continues on. New study shows that the measurement of the Hobbit skull is within the range of microcephalic H. sapiens. Taking the measure of a hobbit

From left to right: Homo floresiensis (LB1) and Homo sapiens.

Homo sapiens (early and modern humans)

• Early humans have been playing hanky panky with Neandertals and possibly the Denisovans. Proof? A toe bone and its DNA. Stone Age toe could redraw human family tree

• A particular segment of our X-chromosome were inherited from Neandertals. This supports the hypothesis that early humans interbred with Neandertal. However, only non-African humans have this segment. Confirmed: All non-African people are part Neanderthal

• Might not be a conscious decision, but apparently early humans that left Africa interbred with Neandertal to protect themselves against diseases. This is probably an unintended result more than an active thought process. First modern humans protected themselves against disease after leaving Africa by ‘interbreeding with Neanderthals’

*Bouchra child, Homo sapiens*

• Dr. Harold Dribble and his team found the skull of “world’s oldest human child” dated around 108,000 years old in Morocco and nicknamed it Bouchra. The boy died when he was 8 years old. This specimen has not been described in any scientific paper so watch out for it soon. World’s Oldest Child Found in Morocco

Recent archaeological find in Koobi Fora, Kenya suggests that our early ancestors might have dined on “seafood” to compensate for the energy needed for the expansion of the brain. The excavated site dates 1.95 million years ago, which predates Homo erectus, reveals distinct faunal remains (some with evidence of butchery) and Oldowan artifacts. Detailed in latest PNAS edition, archaeologist David Braun and his team found an assemblage of bones from terrestrial and aquatic animals such as fishes, turtles and even crocodiles along with stone fragments (Oldowan tools) that are thought to be used to cut these animals with.

Braun posits that if these early hominins indeed ate these terrestrial and aquatic animals (fishes, turtles and crocodiles), then they would have ingested enough calories and fatty acids needed for the expansion of the brain without having to scavenge for animal remains. Braun thinks that these small-bodied hominins would have avoided the dangerous risk of confronting with larger scavengers.

Read more:

Crocs and fish key to human evolution on PhysOrg.

Did Dining on Seafood Help Early Humans Grow These Big Brains? on Discover.

Fossils Suggest Menu That Made Humans Possible on Wired.

Early hominin diet included diverse terrestrial and aquatic animals 1.95 Ma in East Turkana, Kenya (Braun et al., 2010) on PNAS.

Originally posted on The Prancing Papio.

I just love saying, “Another Homo in the family”! Anyways, it seems like a new species of Homo has been identified from a partial skull found in Sterkfontein Caves, near Johannesburg by anthropologist Dr. Darren Curnoe from University of New South Wales (School of Biological, Earth and Environmental Sciences) and paleoanthropologist Dr. Phillip Tobias. This specimen, known only by its museum catalog name Stw 53, was  found in 1977 and had largely been ignored until Dr. Curnoe restored and reconstructed the skull with Dr. Tobias. They had initially concluded that Stw 53 is a Homo habilis but after years of examination and comparing it with other fossils, they are both confident that Stw 53 is a new species and named it Homo gautengensis.

Side by side comparison. Stw 53 (Homo gautengensis), (left) and KNM ER 1813 (Homo habilis), (right). H. gautengensis photo by Dr. Darren Curnoe and H. habilis photo from Wikipedia.

Dr. Curnoe believe that H. gautengensis predates H. habilis, making it the earliest Homo in our family tree so far. H. gautengensis walked upright in southern Africa about two million years ago until 600,000 years ago. Fully grown, it stood about 3 feet tall (just over 1 meter tall) and weigh about 110 lbs (about 50 kilograms). It has relatively large molars and premolars, which suggest that its diet consist large of plant matter and requires a lot of chewing. There were stone tools found near Stw 53, described as “fairly primitive” by Dr. Curnoe. They are also thought to have the knowledge of fire, perhaps using it to obtain and/or prepare food. Stw 53 was found in the same caves with Australopithecus africanus and Australopithecus robustus (or Paranthropus robustus). However, Dr. Curnoe does not believe that H. gautengensis gave rise to Homo sapiens.

Reference:

Beale B. 2010. New species of human ancestor identified. Retrieved May 21, 2010 http://www.science.unsw.edu.au/news/new-species-of-human/

Originally posted on The Prancing Papio.

DNA analysis from a finger bone unearthed from Denisova Cave, Siberia might lead to the discovery of an unknown hominin. Dubbed “X-Woman”, information from her mitochondrial DNA suggests that she shared a last common ancestor with modern human and Neanderthals about one million years ago.

Since Neanderthals and modern humans split at about 500,000 year ago, it suggests that she did not originate from that divergent. Instead, she represents an unknown hominin lineage, presumably an unknown migration out of Africa. “X-Woman” is too young to be a descendant of Homo erectus (which migrated out of Africa to Asia about two million years ago) yet too old to be a descendant of Homo heidelbergensis.

“Whoever carried this mitochondrial genome out of Africa about a million years ago is some new creature that has not been on our radar screens so far,” said co-author Professor Svante Paabo, also from the Max Planck Institute for Evolutionary Anthropology.

Read more about this discovery on BBC News, DNA identifies new ancient human.
Said article can be found on Nature, The complete mitochondrial DNA genome of an unknown hominin from southern Siberia (Krause et al., 2010). Unfortunately I do not have access to said journal so if you have a copy I’d appreciate it A LOT if you can send it to me.

Originally posted on The Prancing Papio.

Researchers from Stony Brook University Medical Center in New York confirmed that the Hobbits, or Homo floresiensis, are indeed a separate “human” species instead of a population of diseases Homo sapiens. The 7th Human Evolution Symposium, Hobbits in the Haystack: Homo floresiensis and Human Evolution was held this year at Stony Brook.

According to the press release, researchers William Jungers and Karen Baab used statistical analysis on the skeletal remains of LB1 (nicknamed Flo) to determine that Homo floresiensis are indeed a distinct species. A few characteristics of LB1 that makes her and her kind a separate species than modern humans.

• LB1′s cranial capacity is about 400cc, about the same size as a chimpanzee.
• The skull and jawbone of LB1 is more primitive looking than any normal modern humans.
• The thigh bone and shin bone of LB1are much shorter compared to modern humans including Central African pygmies, South African KhoeSan (formerly known as ‘bushmen”) and “negrito” pygmies from the Andaman Islands and the Philippines. Jungers and Baab believe that these are primitive retentions as opposed to island dwarfing.
• Using a regression equation developed by Jungers, LB1 was about 3 feet, 6 inches (106cm) tall, far smaller than modern human pygmies whose adults grow to less than 4 feet, 11 inches (150cm) tall.

Read more about the Hobbits at The geometry of hobbits: Homo floresiensis and human evolution (Free Wiley Interscience PDF).

Originally posted on The Prancing Papio.

Two interesting articles that went into my inbox today: Modern man a wimp says anthropologist and Darwin Lives! Modern Humans Are Still Evolving.

Modern man a wimp says anthropologist from Reuters, summarizes Peter McAllister’s book Manthropology: The Science of the Inadequate Modern Male. Using various data from Neanderthals and ancient aboriginal populations, McAllister concludes that modern men are inferior than their predecessor in running, jumping, and even sheer brute. “Any Neanderthal woman could have beaten former bodybuilder and current California governor Arnold Schwarzenegger in an arm wrestle”, McAllister said. John Hawks from John Hawks Weblog has a lot to say about this in his post Is modern man a “wimp”? I think Hawks is spot on with his post.

The Time article, Darwin Lives! Modern Humans Are Still Evolving, is about a study in a contemporary Massachusetts population led by Stephen Stearns and his team of scientists from Yale University. Using correlations between women’s physical characteristics such as height, weight, blood pressure, and cholesterol levels with the numbers of offspring produced, they found that “stout, slightly plump, but not obese” women tend to have more offspring as oppose to women with very low body fat count, as well as women with lower blood pressure and lower cholesterol levels.

Stearns explains that women with very low body fat count, low blood pressure and low cholesterol levels do not ovulate. Ovulation is, of course, when the matured ovarian follicle ruptures and discharge an ovum (or the egg). While human females ovulate about once a month, female chickens ovulate once a day. Of course, we refer to chicken ovum as chicken eggs.

Stearns and his team thinks that the characteristics for producing maximum offspring (stout, slightly plump, higher blood pressure and cholesterol levels) were passed down from mothers to daughters. Separating social and cultural factors using statistical analysis, Stearns and his team were able to conclude that these characteristics were passed down genetically. “Variations in reproductive success still exist among humans, and therefore some traits related to fertility continue to be shaped by natural selection” Stearns says. So women who have more children are more likely to pass down these traits to their offspring.

It explains the notion that modern humans are still evolving because variation in reproductive success means that there are selective pressure that favor certain traits. Interesting to note that while fertility is being shaped by natural selection (as per Stearn and his team’s study), artificial selection is also shaping the width of female pelvis and the average brain size of infants being born. Mothers with a narrow birth canal (smaller pelvis size) puts both her and her infant in jeopardy during childbirth. The infant will be stuck in the birth canal due to restricted space. An infant with a larger than average brain size will also get stuck in the birth canal. Both scenarios will likely kill the infant and mother. However the advent of Caesarean section negates the restriction of a narrow birth canal and allows infant with larger brain size to be born.

So, we can see that modern humans are evolving through variation in reproductive success, female pelvis size and average infant brain size is also evolving through artificial selection though it is too early to say which direction the selection is favoring.

Originally posted on The Prancing Papio.

The controversies over the hobbits or Homo floresiensis just refuse to end. It seems that the hobbits might not be a Homo after all. I guess they found the index and ring fingers of the hobbits (Sorry, inside joke. Read this post if you want).

Anyway, Peter Brown from the University of New England who first described Homo floresiensis said that he is considering of stripping the hobbits from the genus Homo. Brown and his colleague, Tomoko Maeda, said that the Homo floresiensis lineage possibly left Africa before the evolution of the genus Homo. Their paper had been accepted and will be published in an upcoming special Homo floresiensis edition of the Journal of Human Evolution.

I can’t wait for the paper to come out. In the meantime, you can read this article from The Australian.

Originally posted on The Prancing Papio.

That is what University of Liverpool’s Emma Nelson probably would have said if she were to meet our hominan ancestors in person. Known to hold true in anthropoids (humans, apes and monkeys), the index (second digit) to ring (fourth digit) fingers ratio or 2D:4D is an indication of how much an individual were exposed to androgen (such as testosterone) in the womb. The more androgen you are exposed to, the longer the ring fingers are (and the shorter the index fingers are compared to the index fingers).

Nelson et al. believe that a high ratio (longer index finger, shorter ring finger) suggests monogamy (or pair-bonded) while a low ratio (shorter index finger, longer ring finger) suggests polygamy (or non pair-bonded). Simply put, individuals with high androgen level is likely to be non pair-bonded and the telltale sign is in the index and ring fingers. Also, some controversial studies had suggested that both men and women who receive high levels of androgen in the womb are more likely to be stronger, faster, and more sexually competitive.

Nelson and her researchers recently looked at the fossils of two Neandertals and one Australopithecus afarensis with complete index and ring fingers to determine their 2D:4D. They found that Neandertals had long ring fingers, suggesting that they were polygamous just like modern day primates that live in groups. A. afarensis on the other hand, had long index fingers. Nelson is puzzled by this discovery. “These were small creatures that probably lived in groups and were being eaten by predators. How do you keep from mating with different members of the group?”, she said.

Indeed it does not make sense for A. afarensis to be monogamous if they live in groups. Notice that Nelson et al. only used one A. afarensis fossil to get the 2D:4D. Perhaps it is not their fault that only one A. afarensis specimen had complete index and ring fingers but such are the dilemma of using fossil specimens to generalize a whole species.The result might just be a statistical outlier. However, I can’t speculate the result or the implications but anyone that are familiar with statistical data knows that a small sample size leads to a higher sampling error. Also what would a 2D:4D = 1 (same index and ring finger length) be?

Interesting enough, John Hawks at John Hawk’s Weblog mentioned the correlation of 2D:4D with male homosexuality (Robinson and Manning, 2000). I would know about this. In fact, my 2D:4D is indeed low.  Robinson and Manning predicted right! Maybe …

I do find both Nelson et al. and Robinson and Manning (2000) research interesting but I would like to stress that the results are mere predictors and correlations. Take it with a grain of salt. Don’t go measuring 2D:4D of your future spouse, boyfriend or girlfriend and accuse them of not being monogamous or a homosexual.

Emma Nelson and her team presented their research at this year’s Society for Vertebrate Paleontology meeting held in Bristol, United Kingdom. Read more about Emma Nelson’s research.

References:

Reilly M. 2009. Human Ancestors Conflicted on Monogamy. Discovery News. Retrieved September 25, 2009, from http://dsc.discovery.com/news/2009/09/24/human-monogamy.html

Robinson SJ. Manning JT. 2000. The ratio of 2nd to 4th digit length and male homosexuality. Evolution and Human Behavior 21(5): 333-345. [doi:10.1016/S1090-5138(00)00052-0]

Originally posted on The Prancing Papio

Speaking of the Johansons and fossils …

Earlier this year, I’ve blogged about the 2009 Human Evolution Leakey Symposium at Stony Brook that I went to. For more about that blog post, click here.

The symposium, entitled “Hobbit in the Haystack: Homo floresiensis and Human Evolution” can now be streamed live through the Stony Brook website. The website also includes previous Human Evolution Leakey symposia. Click here to watch.

Thanks to Afarensis: Anthropology, Evolution and Science for the heads up!

Originally posted on The Prancing Papio

New analysis by a team led by Australian National University doctoral student Debbie Argue showed that Homo floresiensis, nicknamed hobbits, were early hominin and walked out of Africa to Flores. Their findings supports the argument that Homo floresiensis had a unique wrist anatomy that originated from a lineage that lived long before the common ancestor of Homo sapiens and Neanderthals.

With Mike Moorwood from University of Wollongong and Thomas Sutikna from Indonesian Center for Archaeology, Debbie Argue compared 60 skulls and skeletal features from two individual hobbits to those of hominins, chimpanzees and gorillas using cladistic analysis. The result shows that Homo floresiensis “probably took one of two evolutionary paths from Africa to Flores. One began 1.66 million years ago, the other 1.9 million years ago”.

Read more here: Hobbits Walked Out of Africa

Originally posted on The Prancing Papio.