Anthropology.net

It has been a while since I blogged anything on paleoanthropology. But once I saw John Hawks‘ post where he pointed out Elizabeth Culotta’s news piece in the latest Science on a new hominin femur from Galili, Ethiopia, I was excited. The femur was presented by Bence Viola to the Society of Vertebrate Paleontology, which meet for their annual get together about two weeks ago.

Galili, Ethiopia

Very recent argon-argon dating was done on, and Viola shared those to the Society. The bone is somewhere between between 4.38 million and 3.92 million years old. The bone indicates the individual was larger than lucy but isn’t complete. From what Culotta says, it seems as the distal end is broken off.

The anatomy of the head and neck of the femur suggest the owner was bipedal. But, the distribution of cortical bone around the femur is even. Arboreal primates have an even distirbution of cortical bone around the neck of the femora. The force of gravity and the weight of a bipedal individual causes a lot of stress on the lower half of the femoral neck. It has been observed that the cortical bone of femoral necks of bipedal hominids is thicker on the lower half, as a response to this stress. If you know anything about the debate between the Orrorin camp and the Ardipithecus camp, this should be all too familiar of a discussion.

I first read about hominid remains from Galili in this 2004 piece, which reported on the discovery of an almost complete lower right third molar (GLL 33) likely that of a male Australopithecus afarensis. Hawks pointed out a recent paper which describes the paleoecology of Galili — a open woodland to bushland ecosystem at a time when A. afarensis began replacing A. anamensis. So it is certainly possible that a semi-arboreal/bipedal hominids were navigating this terrain… But, Yohannes Haile-Selassie, who is also working on a 4 million years old hominid from Ethiopia, isn’t too convinced.

What do you think?

E. Culotta (2008). SOCIETY OF VERTEBRATE PALEONTOLOGY 68TH ANNUAL MEETING: Two Legs Good Science, 322 (5902), 670-671 DOI: 10.1126/science.322.5902.670b

A new paper in the open access journal PLoS Genetics reports on a comparison of genetic, geographic, and linguistic patterns of the diverse populations found on the major islands of the Bismarck Archipelago and Bougainville, Melanesia. The paper is titled, “Genetic and Linguistic Coevolution in Northern Island Melanesia.” I think that Simon Greenhill of HENRY may know a bit more about these populations, languages and region than I, but I’m gonna still try and summarize the paper and briefly discuss the results.

The earliest inhabitants of the area arrived around 40,000 years ago, but there was an additional migration into the region about 3,300 years ago. We know that primarily because of the linguistic diversity. The two major languages are Oceanic and Papuan. Oceanic, being a major branch of the widespread Austronesian language family, and the Paupuan languages, likely descendants of languages spoken by people who began arriving in the region more than 40,000 years ago. The rugged geography of the region has been a cause for a lot of the diversification. Despite their regional affinities, the two languages do not form a very coherent language family.

Genetic, Geographic & Linguistic Distances Of Melanesian Popultions

The study sampled 776 individuals from 33 linguistically based populations, which averages to about 23 individuals per population. Each individual was typed on 751 different autosomal microsatellites. The languages were compared on 108 different structural linguistic features. The authors applied two different tests to figure out if genetic and linguistic similarities were formed following early population splits and isolations or if the genetic and linguistic similarities were formed through continuing genetic and linguistic exchange between neighboring populations.

The authors were able to figure out that genes moved freely than languages between nearby populations, regardless of the language family (compare Figures B to D). Language exchanges, on the other hand, have been particularly limited between neighboring Oceanic and Papuan languages (check out Figure D & F). In certain regions, like the rugged interior of the largest island, New Britain, the authors found strong correlations between genetic, linguistic, and geographic distances when compared to their less restricted coastal neighboring populations. They are almost always distinctly different. While extremely restricted to several islands, this study shows us a scenario where language barriers do not particularly hinder genetic exchange, but geography still does.

Keith Hunley, Michael Dunn, Eva Lindström, Ger Reesink, Angela Terrill, Meghan E. Healy, George Koki, Françoise R. Friedlaender, Jonathan S. Friedlaender (2008). Genetic and Linguistic Coevolution in Northern Island Melanesia PLoS Genetics, 4 (10) DOI: 10.1371/journal.pgen.1000239

The Phoenician Alphabet

The Phoenician civilization is understood to be the dominant maritime trading culture between the period of 1550 BC to 300 BC. While they were based out of the Levant, their city-states were spread all across the Mediterranean. The golden age of Phoenician culture and seapower is usually placed around 1200–800 BC. When Cyrus the Great conquered Phoenicia in 539 BC, he divided the Phoenicians into four vassal kingdoms by the Persians: Sidon, Tyre, Arwad, and Byblos. Each flourished, building fleets for the Persians against the Greeks. But their autonomy as distinctly Phoenician people declined after this. The lasting and most important cultural legacy of Phoenicians on modernity is their alphabet. It is generally thought that their alphabet is the ancestor of most modern alphabets.

Okay enough of a history lesson, a team of researchers developed a set of algorithms to detect the subtle genetic impact of historical population migrations. They’ve tested out their formulas on 1,330 men in hopes that they’ll be able reveal the genetic legacy of the Phoenicians. Specifically, they have made a new set of tests that seek out patterns in genetic signatures of modern men. They’ve published their research in the the American Journal of Human Genetics under the title, “Identifying Genetic Traces of Historical Expansions: Phoenician Footprints in the Mediterranean.”

The team sampled Y chromosomes of men from historic Phoenician trading centers in the Mediterranean regions of Syria, Palestine, Tunisia, Morocco, Cyprus, and Malta. After genotyping them, they compared them on 11 STRs and 58 Y-SNPs markers. They weeded out background variation from previous Neolithic migrations, and singled out more widespread Greek colonization events from isolated Phoenician expansions, such as the Phoenician colonization of Tunisia.

The Phoenician Genetic Footprint In the Mediterrenean

The authors were able to detect a half dozen haplotypes and they call them Phoenician Colonization Signals (PCS). PCS3+ is calculated to be the strongest Phoenician-colonization candidate. It is tightly associated with the SNP haplogroup E3b, but it does not show the wide geographic coverage that the other PCS+s demonstrate. Both PCS1+ and PCS2+ score well, although not as strongly as PCS3+. The excess of haplogroup J2, and PC1+ to PS3+ in coastal Tunisia, the site of Carthage, compared to inland Tunisian populations is exceptionally significant, and suggests that the Roman destruction of Carthage did not eliminate the Carthaginian gene pool. So the presence of these seven related genetic lineages in places around the Mediterranean Sea, tell us that where Phoenicians had lived and persisted genetically.

These lineages suggest that the Phoenicians contributed their genes to at least six percent of modern populations of historic Phoenician trading outposts. In fact, one boy in each school class from Cyprus to Tunis may be a direct male-line descendant of the Phoenician traders.

Of course, since this is only a Y-chromosome test, we’re only getting part of the genealogical history. If a Phoenician man fathers only daughters, his Y-chromosome lineage dies out. That means tests likes these can only say something when there’s an unbroken male line in that area. It is certainly possible that more people from Cyprus to Tunis have a Phoenician heritage. Dienekes, a Greek, has a scathing criticism of the paper. This paper explicitly says they didn’t try to seek out Greek expansion but Dienekes outlines six shortcomings, related to Greek expansions, that the paper didn’t factor that would affect these conclusions — he ends his post saying,

“Is there anything of value in this paper? Well, it’s a good idea to try to correlate Y-chromosome distribution with historical rather than pre-historical events. Too bad the authors botched the job, but their paper can at least serve as a reference point for how not to go about doing it.”

Pierre A. Zalloua, Daniel E. Platt, Mirvat El Sibai, Jade Khalife, Nadine Makhoul, Marc Haber, Yali Xue, Hassan Izaabel, Elena Bosch, Susan M. Adams, Eduardo Arroyo, Ana María López-Parra, Mercedes Aler, Antònia Picornell, Misericordia Ramon, Mark A. Jobling, David Comas, Jaume Bertranpetit, R. Spencer Wells, Chris Tyler-Smith, The Genographic Consortium (2008) American Journal of Human Genetics. DOI: 10.1016/j.ajhg.2008.10.012

Last month I was excited to share some research about the chemical composition of Ötzi, the 5,000 year old Tyrolean Iceman that has captured my attention for quite sometime. Today, I’m even more excited to share that the complete mitochondrial genome of Ötzi has been sequenced using a combination of PCR amplification and 454 sequencing. The research has been published in Current Biology. You can find it under the title, “Complete Mitochondrial Genome Sequence of the Tyrolean Iceman.”

I’ve covered the details behind Ötzi before. I’ll give you a quick run down in case you forgot or never knew about him. Ötzi is the name given to mummy discovered on September 19^th, 1991, around 3,270m above sea level, in the Eastern Alps near the Austro-Italian border. His remains were dated to be , 5,350–5,100 years old, and was remarkably preserved because of the cold climate. We have an idea what his last meal was and what he wore. He’s thought to have been around 46 years old, his fertility has been questioned, and his cause of death seems to have been rather horrific — severely wounded by an arrow and some blunt force trauma to his face.

Previous researchers have sequenced some of his mitochondrial genome, specifically the hypervariable segment (HVS-I). Two nucleotide transitions, at positions 16224 and 16311, indicate that Ötzi’s mtDNA belonged to haplogroup K, a subclade of the major west Eurasian haplogroup U. The authors of the new Current Biology paper decided to completely sequence the mitochondrial genome of Ötzi using 454 pyrosequencing technology. They’ve compared the sequence to 115 published complete mtDNA sequences from modern individuals, and constructed a phylogeny of the K haplogroup.

The sequencing run seems to have been rather uneventful. I’ve covered 454 technology before, but to recap it is sequencing by synthesis, which involves template DNA being immobilized, and solutions of each nucleotide added. They hybridize to their complement at the first unpaired base of the template. The hybridization reaction lets off light, because the polymerase enzyme is paired with another other chemiluminescent enzyme. A high resolution photo is taken and any remaining unbound nucleotide is removed and then another wash of another base is made. With the array approach developed by 454, it is possible to generate over 100 million nucleotide data in a 7 hour run with a single machine.

The authors reported they made 45,829 reads, but only 42,695 reads, or 93.2% of the total, were usable. Several gaps in the mitochondrial genome were observed, so PCR products were cloned into vectors and sequenced with conventional Sanger technology. When compared with the revised Cambridge Reference Sequence (rCRS), the consensus sequence showed 30 mtDNA transitions. A phylogenetic comparison was made to all 115 haplogroup K complete sequences currently available. The authors confirm that Iceman’s sequence falls within haplogroup K.

But, transitions at positions 3513 and 8137 on the Iceman’s mitochondrial genome indicate that his maternal lineage belongs a K1 subhaplogroup but not to any of the three subclades into which K1 is currently further subdivided (K1a, K1b, and K1c). The authors conclude that the Iceman’s mtDNA, belong to a novel branch of K1, not yet identified before. They’re calling it K1ö.

I’m not gonna get into much of a discussion about contamination because the samples were taken from thawed tissue from the mummy’s rectum. Many lines of evidence show that there was a lot of endogenous mtDNA that woulda muddled out any contaminating DNA and the results reconfirm the previous HVS-1 results. Anyways, this is the oldest complete H. sapiens mtDNA genome generated to date. The results show that as the frequency of genetic lineages change over time, due to genetic drift, some variants die out. Based upon the mtDNA, it is highly unlikely that Ötzi has any modern day maternal relatives… unless we sequence more than 115 haplogroup K carriers.

Luca Ermini, Cristina Olivieri, Ermanno Rizzi, Giorgio Corti, Raoul Bonnal, Pedro Soares, Stefania Luciani, Isolina Marota, Gianluca De Bellis, Martin B. Richards, Franco Rollo (2008). “Complete Mitochondrial Genome Sequence of the Tyrolean Iceman” Current Biology, DOI: 10.1016/j.cub.2008.09.028

Nature Genetics just published a brief correspondence on the evolution of promoter regions in the human genome. The basis of this study relies on the observation that 46% of promoter regions in the human genome have a higher number of nucleotide substitutions than corresponding introns. The authors don’t make the distinction that positive selection, relaxed constraint or mutation rate are the causes of this observation, but they suggest that they have been important to hominid evolution and the genetic diversity of humans.

If you don’t know what a promoter is, I’ll give you a quick run down. Promoters are regions of the genome that are upstream from genes. Regulatory elements such as transcription factors bind to these regions and either start the expression of the gene that is downstream or regulate expression. Any changes to these region can affect phenotypes related to the gene downstream. Between two populations with the exact same intronic sequence of a gene, a difference in the promoter region can have dramatic effects.

In this current paper, “Rapidly evolving human promoter regions,” the authors respond to a previous paper on the subject. They reanalyzed the alignments used by the previous paper. They asked whether each promoter region as a whole is evolving more rapidly than local intronic sequences. They find that almost all (569/575; 99%) of the promoter regions identified by the previous paper as containing positively selected sites have a higher average substitution rate than their paired intronic regions.

The previous authors say that positive selection is at play. They based this conclusion on positive selection on introns. But the current authors caution that promoters are unusual genomic regions, and cannot be compared to selection on introns. They simiply conclude that promoters have higher neutral substitution rates. The previous authors respond to this in this same issue of Nature Genetics. They defend that the current authors methodology “do[es] not affirm their contention that mutation is generally accelerated in primate promoters.” Either way, both teams have identified that promoter regions of the human genome are highly diversified. The reason why they are, is still unresolved, but these conclusions do fall in line with previous ones that I’ve covered here on Anthropology.net:

• Differences of gene expression between human populations
• Identifying Cis-Acting Elements that regulate Human Gene Expression
• Gene Regulation, the driving force in Human Evolution
• Understanding Adaptive Evolution in the Human Genome

Martin S Taylor, Tim Massingham, Yoshihide Hayashizaki, Piero Carninci, Nick Goldman, Colin A M Semple (2008). Rapidly evolving human promoter regions Nature Genetics, 40 (11), 1262-1263 DOI: 10.1038/ng1108-1262

Ralph Haygood, Olivier Fedrigo, Gregory A Wray (2008). Reply to “Rapidly evolving human promoter regions” Nature Genetics, 40 (11), 1263-1264 DOI: 10.1038/ng1108-1263

As you may have noticed, I’ve taken a bit of a blogging hiatus. I have actually taken the time off to write some software in Python that I hope to release soon… a project that you may have seen in previous iterations.

Speaking of some software, I have do have some less cryptic news to share with you. I have been a part of the development team behind FOROST, a forensic osteology metabase, that physical anthropologists and forensic specialists may find useful since it provides images and descriptions of special pathological and taphonomic cases. We’re ready to showcase the site and encourage you to use it and pass it onto others!

This metabase primarily functions to expand one’s access to comparative samples. By providing a portal to well documented images and attribution, we foresee that FORST will help connect investigators to collections that they may have never knew about. We’ve decided to call it a metabase because we’ve decided not to house the images and metadata linked to each specimen. Rather, we curate a subset of the information, which is determined by contributors, and is in turn searchable from the FOROST query builder. Each item in the database is ultimately stored on the participant members’ servers and is branded to their liking. I am hopeful that this unification of forensic data will pool together distributed specimen information while retaining individual attribution. I’m even more hopeful that it will facilitate collaboration and standardization of forensic criteria. It is like one big digital potluck party…

The metabase is queriable now. You can poke around and see how we’ve gone about showing the results from the preliminary institutions that have participated. You’ll find some pretty cool images of blunt force trauma and gunshot wounds. I’ve worked with a close colleague of mine, Dr. Henry Gilbert, who approached me with the idea a while back ago. My role has been primarily a consultant, where I’ve helped with brainstorming the database design, setting up the development environment and PHP coding practices. The senior developer is Raul Castillo. I recently started making a translation of the site into Farsi, as well. I have also had the pleasure to work with researchers and developers from UNAM.

I really am excited about this project and I’d really like to hear your feedback. We’re far from calling it a completed project and understand it may have some quirks here and there. I want to know about your experiences using the metabase. You can shout out your ideas and suggestions for improvements here in the comments thread, or you can send the project manager, Socorro Baez, an email, if you prefer the private route. You should also contact her if you want to participate too.

Oh yeah! FOROST will also be announced at a conference at the Instituto de Investigaciones Antropológicas, at UNAM on the 16th to the 20th of March, 2009. I plan on attending the conference, which will host talks by Carlos Serrano Sánchez and Douglas Ubelaker, as well as others. If you’re interested in how forensic science intersects with anthropology, I recommend you attend. Let me know if you do decide to go, maybe we can have a meetup of Anthropology.netters.

Both Dienkes and John Hawks have shared news about the latest research on the domestication of dogs. The researchers analyze 117 skulls of prehistoric canids from sites in Belgium, Ukraine and Russia. They conclude that a 31,700 year old canid from Belgium is ‘clearly different from the recent wolves, resembling most closely the prehistoric dogs.’

The draft can be found in the Journal of Archaeological Science under the title, “Fossil dogs and wolves from Palaeolithic sites in Belgium, the Ukraine and Russia: osteometry, ancient DNA and stable isotopes.” If the dating, and phylogenetic analysis is correct, these remains makes them the oldest known remains of domesticated dog, pushing back domestication time by 17,700 years, since the second oldest known dog, found in Russia, dates to 14,000 years ago as explained by Carl Feagans.

Doral View of the Goyet Cave Dog (a) and wolf skulls (b & c)

Prehistoric dogs are distinguished from both prehistoric and extant wolves in having a shorter and broader snout, relatively wider brain cases, and a general reduction in skull size. Palaeolithic dogs in the study conform to this pattern. The researchers extended their anatomical analysis to mtDNA and stable isotopes on the Belgian samples. All fossil samples yielded unique DNA sequences, Dienekes pointed out the results:

“when compared to extant wolf and dog sequences available from GenBank, all seven haplotypes found in the Pleistocene samples were found to be unique and not described to date. This result is remarkable when considering the large number of wolf (~160) and particularly dog sequences (> 1,000 from almost all breeds known today) available in Genbank.”

What this indicates is that prehistoric canid diversity was much larger than it is now. That makes sense, part of the domestication process, i.e. selection for desirable traits, weeds out diversity. It is certainly possible that these dogs were one of the first domesticated canids. The isotopic analysis of the dog remains indicate that they ate large game like horse, musk ox and reindeer, but not fish or seafood.

The dog remains come from an adjacent horizon in the Goyet cave, Belgium where Middle and Upper Paleolithic artifacts were discovered along with numerous remains of ice age mammals. Some of the remains show percussion fractions, have cut marks, or display traces of ochre. Aurignacian ivory beads were also discovered. The ancient Belgian canids are considered to be domesticated dogs because of their anatomy, unique isotope profile (they were eating large game, presumably hunted by humans), and since the remains came from a cave with recurrent human occupations from the Pleniglacial until the Late Glacial. This is exciting, but the authors caution that it is not very clear from which horizon the artifacts and bones originate from, if the same horizon at all. I consider the association rather loose.

Also, as John Hawks wonders, why’s there almost a 20,000 year gap in the fossil record of the domesticated dog? Most people share Dienekes opinion that dogs are extremely advantageous, one would expect a consistent representation in the fossil record — not a massive intermission.

M GERMONPRE, M SABLIN, R STEVENS, R HEDGES, M HOFREITER, M STILLER, V JAENICKEDESPRESE (2008). Fossil dogs and wolves from Palaeolithic sites in Belgium, the Ukraine and Russia: osteometry, ancient DNA and stable isotopes Journal of Archaeological Science DOI: 10.1016/j.jas.2008.09.033

Bergmann’s rule is an observation that body mass of endotherms increases with altitude and colder climate. Neandertals fit this rule, their barrel chests and wide hips, indicate they had large bodies, and thus smaller surface area relative to their body mass. This feature made them comparatively inefficient at radiating their body heat off into the surrounding environment than smaller bodied hominins…. which is an advantageous trait to have in cold environments.

Another similar theorem, Allen’s rule, summarizes the observation that endotherms from colder climates usually have shorter limbs compared to counterparts from warmer climates. Similar to Bergmann’s rule, shorter limbs keep blood and heat closer to the core of the body, reducing heat loss.

All this may sound like adaptionist mumbo-jumbo, but researchers have observed these adaptations to cold climate in other animals. Compare the profiles of polar bears, walruses, and mammoths to cheetahs, antelopes, and giraffes, and you’ll see how some of this makes sense.

Homo neanderthalensis from la Chapelle aux saints

Anyways, I digress. There are two different camps currently hashing out whether the Neandertal facial morphology is due to random genetic drift or a mix of archaic traits and climate influenced adaptations. One of the more hotly debated facial traits, the Neandertal nose, doesn’t quite fit what we expect to see in cold climate adapted species. The Neandertal nose is broad and wide, a feature seen in tropical climates. Physiologists have shown that narrow noses better warm the air being inhaled and prevent evaporation of water in such dry environments by recapturing moisture during exhalation. Wide noses dissipate heat very efficiently.

Some researchers, like Milford Wolpoff, have suggested that there’s a growth and development reason to why we don’t see narrow Neandertal noses. For example, the effects of large teeth and broad palates could have affected the reduction of the nasal aperture, and were most likely inherited traits from Pleistocene ancestors. In a new Journal of Human Evolution paper that Dienekes pointed out this week, researchers from the University of Iowa have investigated the relationships between nasal breadth, intercanine breadth, and facial prognathism. The paper is titled, “The paradox of a wide nasal aperture in cold-adapted Neandertals: a causal assessment.” They tested variants of the following hypothesis: Does the distance between the two upper canines correlated with nasal breadth in modern and archaic Homo?

Intercanine Breadth Measurement

Their sample set of modern humans included 119 crania of Bantu people and 112 crania of Western Europeans. The sample of human ancestors included 11 from the early Upper Paleolithic, 9 from the late Upper Paleolithic all coming from Eurasia. They also included 15 samples from the late Stone Age in Africa, and 14 Pleistocene Homo. Like I mentioned earlier, they measured the distance between the two canines, known as the ICB. In anatomical terms that’s the distance between the lingual tubercles of the maxillary canines, or the pointy parts of your vampire teeth. The lower facial prognathism (BPL) is a measurement of basion to prosthion. Upper facial prognathism (BNL) is a measurement of basion to nasion. Of course some fossils didn’t have all the measurements so predictions were made by least squares regression.

The authors conclude that intercanine breadth cannot fully explain nasal breadth from their sample set, which goes against what anatomist Gustav Schwalbe said in the later 1800′s and what E.V. Glanville reconfirmed in the late ’60s. They also note that the development of the anterior palatine bone does not affect the growth trajectory of the breadth of the nose. While, they do suggest that nasal breadth is affected by the ICB, the lower facial prognathism impacts nasal breadth more than any other trait.

They finally suggest that the plesiomorphic retention of a prognathic lower face is due to the extended time the premaxillary sutures remain open during development. This is lower face prognathism is not a derived trait, but rather a retention of archaic traits, seen in early humans. But that’s not to say the Neadertal nose never adapted to cold climates while the rest of their body did. Neandertals from colder climate have been characterized with a more narrow superior nasal dimensions, which have ultimately been linked to aspects of airflow dynamics.

N HOLTON, R FRANCISCUS (2008). The paradox of a wide nasal aperture in cold-adapted Neandertals: a causal assessment Journal of Human Evolution DOI: 10.1016/j.jhevol.2008.07.001

Razib has responded to my disagreement with his statement that any given hunter-gatherer infant is far more likely to reach reproductive age than any given offspring of peasants. And he’s confident with his standing. I’ve done some reviewing of the literature and I still think that the probability that a child of an agriculturalist will reach reproductive maturity is higher than that of a hunter gatherer. Hell, that’s why there’s been a population boom ever since the Neolithic revolution. Anyways, in my previous post I outlined some of the ethnographic reasons why I think so. In this post, I’ll share some of the demographic data that supports my hypothesis.

On page 198 of the text, Hunter-Gatherers: An Interdisciplinary Perspective average parity rate for healthy hunter-gather women, Renee Pennington explains that the average fertility rate for a hunter-gather woman is 6-8 births during her lifetime. The expected child-bearing age of hunter-gatherer women ranges between 24 and 37 years. The data comes from surveys of hunter-gatherers in the early 1990′s.

I averaged out the 2008 total fertility rate (TFR) of all countries provided by the CIA. I couldn’t find TFRs for strictly agricultural populations so I will assume that most, if not all the countries, are agricultural given that  very few large hunter-gather populations exist. The average fertility rate is around 1-4 births during a modern day agriculturalist woman’s life time. The factbook mentions that the child-bearing age for women surveyed is between 15-49 years old.

Given this, I think we can see that hunter-gatherer women birth more frequently within a more restricted time frame. Part of this is due to affects of a hunter-gatherer lifestyle. But one of the flaws with my assumption that modern TFRs provided by the CIA come from agriculturalists can be seen already, because we know that agriculturalists have on average more children than hunter gatherers. Razib mentioned Fischer’s review of birth rates in colonial New England was upward to 10, and I’m not surprised.

Because of this discrepancy, we need to factor in the survivability of the newborn. Razib mentions that there’s a “greater likelihood of dying early among farmers because there were just more of them floating around,” so to compare, I researched the infant mortality rate (IMR) which is defined as frequency of deaths in the first year of life per 1,000 live births. These two tables describes the IMR in modern day hunter gatherers vs the IMR in modern day agriculturalists.

Table 1: IMRs Among Hunter-Gatherers

Table 2: IMRs Among Agriculturalists

My hunter-gatherer data comes from Kramer & Greaves, “Changing Patterns of Infant Mortality and Maternal Fertility among Pumé Foragers and Horticulturalists.” My agriculturalist data has come from differing sources, some from the most recent CIA World factbook, and others from newspapers, research papers, which I’ve linked up. Significant differences emerge when we look at the infant mortality experiences between these two sustenance strategies, almost three times greater infant moralities among hunter-gatherers than their farming counter parts.

Average IMRs of Hunter-Gatherers versus Agriculturalists

Now you could argue that higher IMRs could be due to the lack of exposure hunter-gatherers have to pathogens and health care on average compared to sedentary agriculturalists. That’s precisely why I put the Pumé example in there. The Pumé are a linguistic group of people who live on the border of Venezuela and Columbia. Populations that live in savanna ecosystems are the hunter-gatherers, where river dwelling populations are the farmers. Both populations have similar vaccination patterns, and yet the hunter-gathering population experiences more infant moralities than the farming population.

Why?

Newborns are particularly susceptible to shortfalls in caloric intake. They are dependent on their mother’s milk for calories. I know the agricultural diet is nutritionally deficient, I’m not gonna argue that it is. The farmers’ diet has made us less robust and susceptible to dietary diseases. But it is rich in calories and the greater accessibility to calories that come with agriculture improves likelihood of young children reaching sexual maturity.

The hunter-gatherer diet fluctuates caloric intake based upon the availability of food sources and cultural taboos, and that has deep impacts on their survivability. You can see from the data that I presented that 1/3 of all hunter-gatherer newborns will die before 1 year. I didn’t extend later life mortality rates, but to summarize, those that do survive half live to see the age of 15. So for every 8 births, a hunter-gatherer woman gives, only 6 or so are expected to live to childhood. Of those 6, only 3 see adolescence. And of the 3 teenagers, only 1 is expected to reach 50 years old.

Razib equates hunter-gatherers to lions, and farmers to antelopes. Lion cub mortality rates are higher than antelopes, upwards of 80% of cubs do not make it to adulthood. Whereas antelope calves, if they survive predation, have much more greater chances at seeing sexual maturity. It is much more precarious to count on mom to provide milk and hunt at the same time, than it is to graze. So, this issue is less about absolute availability and more about reducing the periodicity and amplitude of nutritional stress. And this is one of the reasons why the agricultural diet has ‘won’ over many humans, even despite the many shortcomings it has.

KAREN L. KRAMER, RUSSELL D. GREAVES (2007). Changing Patterns of Infant Mortality and Maternal Fertility among Pumé Foragers and Horticulturalists American Anthropologist, 109 (4), 713-726 DOI: 10.1525/AA.2007.109.4.713

Dienekes shared the abstract to a paper that seems to completely contradict an earlier study. It is pretty evident from the title of newer study, “Do humans prefer altruistic mates? Testing a link between sexual selection and altruism towards non-relatives,” what the authors tested. And they confirm that there is a linkage between the propensity to be giving and being perceived as a good parent/partner.

The previous study, led by Peter Jonason, suggests quite the opposite — that someone who holds a “dark triad” of traits, like callousness, impulsive behavior, extroversion, and narcissism attract mates more effectively than someone who expressed empathy for others…. Better expressed by the cliché, “nice guys finish last.”

The crux of this difference is between short term mating and long term mate choice and which is more evolutionarily valuable in humans. People who express the “dark triad” of traits have a higher number of sexual partners than those that don’t. These relationships are short term. Some consider this to be successful, in other words, self absorbed traits have persisted because they seem to be advantageous.

But as the new paper shows, increased altruistic personality correlates significantly with the spouse/partner chosen. Humans aren’t mosquitos. Because of the relative developmental immaturity of the human newborn and its dependency on long-term care to reach sexual maturity, the reproductive success of humans isn’t all about ‘spreading the seed.’ This makes us relative K-strategists, where we put an emphasis on high levels of parental care, resource acquisition, kin provisioning, and social complexity and not on gamete production, mating behavior, and high reproductive rates which r-strategists like fish, frogs, etc. emphasize.

Tim Phillips, Chris Barnard, Eamonn Ferguson, Tom Reader (2008). Do humans prefer altruistic mates? Testing a link between sexual selection and altruism towards non-relatives British Journal of Psychology, 99 (4), 555-572 DOI: 10.1348/000712608X298467