Primate Friendships, human mating systems and Bipedalism

There are “pleasure” chemicals in the brains of old human couples (e.g., oxytocin) that are released when they are interacting and feeling happy together that are not the chemicals associated with sex. Our endocrine system wasn’t built overnight.

Literature on primate behaviour in general and human evolution in particular has got me thinking about this male infanticide issue had how it has distorted our view of human evolution. It seems that virtually all the papers for the last 30 years on how and why humans became bipedal and upright assume that males are brutish thugs who only want sex from the females and whose closed relationship is to exchange food for it, and to combat other males over it.

When I began researching a leaf monkey, Trachypithecus cristatus, I read in a secondary reference book that, when a male from outside the troop deposes the troop's alpha male, "He immediately kills all the infants" to make sure that the progeny of the troop are all his, and to bring the lactating females into estrus so he can mate with them. Yet when I dug deeper into the literature, I found that male infanticide has never been observed in this species. It was based on a single 1979 study in which male infanticide had been inferred because all of the infants had disappeared when checked three months later. It was inferred because of a theory, then sweeping the wildlife behaviour literature, that males kill infants not their own to increase the likelihood of their own progeny being born and surviving: the "male infanticide" hypothesis.

I've just now got a stack of 20- and 30-year old primate books from the library, and in one of the chapters about a Trachypithecus species, the two males in a troop (as well as the females) run to grab up the infants for safety when danger threatens. In my own species (the subject of three papers, one published, one in press and one in prep.) male infanticide has almost never been observed and where it occurs is infrequent--perhaps once every several years, in a well-studied group of Trachypithecus leucocephalus, as reported to me by the author of a detailed study. This is contrary to the male infanticide paradigm.

On the contrary, in my own studies on T. cristatus and other studies on at least two other species of this genus, males care for infants and the most aggressive they get is to bark or swat at a juvenile who is pestering them.

In fact, recent reviews of the issue have cast doubt on the extent (number of species) to which male infanticide applies, and the evolutionary significance when it does.

The over-emphasis of male infanticide hypothesis, and the flip side, the females' "infanticide avoidance hypothesis", has worked its way into ideas about homonid evolution. I just can't reconcile seeing Homo sapiens males love and care for their own and other juveniles (how many dads coach their kids' hockey or basketball teams, or take their daughters to ballet? Almost every one I know), and have deep relationships with their wives that go far beyond sex, with this brutish Home erectus / early Homo sapiens paradigm of "food for sex" and "kill all the infants who are not mine" paradigm. I think we’ve been too influenced by baboons, and not enough by gibbons. Somehow we got to be upright, monogamous in complex social systems, and large-brained. I think the archaeologists agree now that upright/bipedal came first and the large-brain/complex social systems came later. But my feeling –nascent though it is—is that we really have to overthrow this male infanticide/food for sex paradigm before we can begin to explore how human relationships developed, and even to understand what they are.

While searching literature on this yesterday, I came across a paper (Niemitz, C. 2010. The evolution of the upright posture and gait—a review and a new synthesis. Naturwissenschaften 97(3): 241-263) that synthesized all the theories about how hominids began walking upright. The author had discounted the hypothesis that the need to carry infants was involved in hominids first walking upright.

I think it is wrong to reject infant carrying as a force in bipedalism, which always assumes that women were doing the carrying and they did it with the infant on their hips or in their arms. But consider:

1. Humans are the only primates who carry infants on our shoulders. The infant grabs the head. Human neonates’ hands are far too weak to securely grasp hair or any other part of the body, but they automatically and effectively grasp the head of the carrying adult.

2. Go to any park and you’ll see families with the dad carrying a toddler on his shoulders, perhaps leading a second by the hand, while the mom cradles an infant on her hip or in a snuggly, perhaps leading a second.

3. Humans vertebral columns can carry a heavy load for an extraordinary distance (many km) and we like doing it so much that, even when not forced to, we do it for fun-go to any national park with wilderness and you’ll see backpackers hiking long distances. Why did we need such strong backs if we carry infants, weapons, food etc. in our hands and arms?

4. ...but we can’t carry even small loads with a slight stoop. Lumbar pain would have been a powerful motivation to stand straighter when carrying.

5. Home erectus could not have walked all the way to China without a way to transport juveniles too large (or too many) for the mom to carry and/or lead, but too small to keep up. Don’t forget that neoteny was progressing: the kids were getting heavier just when our predecessors were roaming farther.

The above has obvious implications for grouping behaviour and mating systems, which in turn are integral to brain size. it’s a package. It is time to reconsider the evolution of bipedalism in the light of research that shows primate males to be more caring and less homicidal of infants. Maybe they got more from their mates than sex; maybe they gave more than food. It is time to conder this along with development of monogamy, societal grouping and dispersal.

Key papers consulted in this essay:

Hrdy, S.B. 1974. Male-male competition and infanticide among the langurs (Presbytis entellus) of Abu, Rajasthan. Folia Primatologica 22: 19-58.

Brotoisworo, E. 1979. The Lutung (Presbytis [Trachypithecus] cristata) in Pangandaran Nature Reserve: social. adaptation to space. Kyoto University, Kyoto.

Van Schaik, C.P., and Kappeler, P. 1997. Infanticide risk and the evolution of male-female association in primates. Proceedings of the Royal Society B: Biological Sciences 264(1388): 1687.

Borries, C., Launhard, K., Epplen, C., Epplen, J.T., and Winkler, a.P. 1999. DNA analyses support the hypothesis that infanticide is adaptive in langur monkeys. Proc. R. Soc. Lond. B 266: 901-904.

Palombit, R.A., Cheney, D.L., Fischer, J., Johnson, S., Rendall, D., Seyfarth, R.M., and Silk, J.B. 2000. Chapter 6 Male infanticide and defense of infants in chacma baboons. In Infanticide by males and its implications. Edited by Carel van Schaik, and Charles Helmar Janson. Cambridge University Press, Cambridge. pp. 123–152.

Zhao, Q., and Pan, W. 2006. Male-immature interactions seem to depend on group composition in white-headed langur (Trachypithecus leucocephalus). Acta Ethol 9: 91-94

Zhao, Q., Tan, C.L., and Pan, W. 2008. Weaning age, infant care, and behavioral development in Trachypithecus leucocephalus International Journal of Primatology 29(3): 583-591.

The Second Amendment in the American Bill of Rights

A survey making the email listserv rounds, apparently sponsored by USA Today, asks: "Does the Second Amendment give individuals the right to bear arms?"

The 2nd amendment in the American Bill of Rights reads, "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."

It does not explicitly give individuals the right to arms. “The People” have this right. (Capitalization of “People” was not in the original draft, but was added to the version distributed to the states.) At best, this is ambiguous, since “people” can be taken to mean individuals, or a government “of the people, by the people and for the people”. The introductory phrase “...well regulated Militia...” seems to lean the whole amendment towards the latter interpretation but, of course, this has been debated ever since it was passed. "well regulated " could also imply restrictions on citizens' right to bear arms, i.e., gun control. In 1791, there was no national army; America won independence with an aggregation of state militias, the raising of which would have been nearly impossible had not a great majority of individuals already had their own weapons. Therefore, for all practical purposes, it can be argued (and has been!) that the amendment implies the right of individuals to bear arms. Unfortunately, it doesn’t say it. Since it is ambiguous, and since the USA Today question asks about rights of individuals, which are not mentioned in the Amendment, I think a strictly literal answer would have to be no. I noticed, however, that 97% of respondents disagreed with me.

From Wikipedia: " One aspect of the gun control debate is the conflict between gun control laws and the alleged right to rebel against unjust governments. Some believe that the framers of the Bill of Rights sought to balance not just political power, but also military power, between the people, the states and the nation,[44] as Alexander Hamilton explained in 1788:

“[I]f circumstances should at any time oblige the government to form an army of any magnitude[,] that army can never be formidable to the liberties of the people while there is a large body of citizens, little, if at all, inferior to them in discipline and the use of arms, who stand ready to defend their own rights and those of their fellow-citizens.[44][45]
“Some scholars have said that it is wrong to read a right of armed insurrection in the Second Amendment because clearly the founding fathers sought to place trust in the power of the ordered liberty of democratic government versus the anarchy of insurrectionists.[46][47] Other scholars, such as Glenn Reynolds, contend that the framers did believe in an individual right to armed insurrection. The latter scholars cite examples, such as the Declaration of Independence (describing in 1776 “the Right of the People to … institute new Government”) and the New Hampshire Constitution (stating in 1784 that “nonresistance against arbitrary power, and oppression, is absurd, slavish, and destructive of the good and happiness of mankind”)."

Anyway, I’m about to pass my (registered) .444 Marlin lever-action with the gold-plated trigger to my son, since he finally got around to getting a federal license to own one. Not owning it yet didn’t preventing him from using it to kill a bear that had eaten 4 of his goats and was threatening my wife and granddaughter two years ago. And had he not, I had it in the sights of my (also registered) .308 at that moment anyway.

Biogeography of Gibbons

I've been struggling on taxonomy of langurs and gibbons lately: langurs because I have an accepted paper "in press" that needs a little tweaking and the tweaks go back to early in the 19th Century; and because the gibbon monograph that I'm starting has taxonomic problems pre-dating Linnaeus 1771.

But the good news is that so many ancient manuscripts are finding their way on to the Internet that I can actually sit here in Coquitlam and read books from that era. And that they're often in French, Dutch, German or Latin doesn't matter so much, because the names of the authors and the journals are all the same, and the Latin names of the critters is still Latin. Takes time, though.

Last night I had an epiphany: I noticed that the 3 Indochinese species of gibbons are separated by big rivers: crested gibbons (Nomascus spp.) east of the Mekong, Lar-type gibbons (Hylobates spp.) between the Mekong and the Salween system, and Hoolock gibbons (Hoolock hoolock) west of there, between the Salween River and the Irrawaddy River. It's because gibbons can't swim, and these big rivers have been stable for long enough for these genera to evolve--that's back to the Pliocene, between 2 and 5 million years.

I'm not the first to notice that large rivers separate gibbon species, nor the first to notice that the biggest rivers separate the genera. But it was fun to figure it out for myself.

The Duality of Racism and Diversity

We have a problem with race in this country. The previous sentence is deliberately ambiguous. Some readers will assume that I think there are too many; that I’m racist. Of those who interpret it thus, most, thankfully, will think I’m despicable. Some few, regrettably, may applaud the sentiment. Others, reading the first line, may think, approvingly, that I’m appalled at people who recognize race at all, whether as an issue or a reality. “We are all one,” they say, implying that our prose should ignore ethnic distinctions.

We happily go to the fall Diwali festival of South Asian culture, or the Chinese New Year parade, but few of us like being forced to reveal our ethnic origins in job applications. So “multiculturalism” is fine, politically speaking, but racial distinctions are not. I don’t mind this duality; it’s how it is. We should celebrate diversity when we can, but keep it out of places where it could subvert equality.

As a scientist, however, I think that it is time to make our discussion of ethnic and cultural diversity more accurate. Wednesday’s reports on the Statistics Canada projections of ethnic diversity uses terminology that is woefully obsolete. I’m not talking about the fact that so many of us are mixtures, but about how we define our ethic origins. The graphs on page A3 encapsulate the conundrum. We think we know what is meant by “Black,” for example, but most of us are wrong, to which I will return in a moment.

We see the “Arab” category and, having just read Douglas Todd’s column on religion, might assume that it equates to “Muslims” since most Arabs are, in fact, Muslim. But my Persian barber, although she would like to have a mosque nearby, speaks Farsi and has little in common, culturally, with Arabs. Most Pakistanis are Muslim, too. Are they in the “Arab” category or “West Asian” (a new one for me)? If we recall the latest atrocities in Darfur, we may think that the camel-mounted raiders from the north of Sudan were Arab because the reporters invariably say so, but they are not. They only speak Arabic—mainly as a second language—because of the Muslim conquests around 1200 years ago. People of Chad, northern Sudan and Ethiopia speak endemic languages such as Nubian, in the Nilo-Saharan language group; Beja, in the Cushitic language groups; and Kordofanian languages. Nilo-Saharan languages predominate in the south. To the west, in Niger, Mali and southern Algeria, the nomad peoples, such as the Tuareg, speak Berber languages. To lump these people in with “Arabs” as is so often seen in newspaper articles, distorts our perspective.

Similarly, “Filipino” is listed on page A3, separately from their relatives elsewhere in Southeast Asia. Here is the problem with this terminology: The Philippines is a country with many languages and cultures, but its genetic and ethnic affiliations are much broader.

Recent genetic, linguistic, and archaeological discoveries have led to a new appreciation of how we came to be whom we are. Fundamentally, we are all Africans. All humans can trace their genetic heritage to eastern or southern Africa about 150,000 years ago. Our forebears spread throughout the southern and western parts of the continent. But then, about 90,000 years ago, climate change and consequent forest expansion isolated groups to the north and south. Over time, the northern group evolved new genetic types and cultures and spread throughout the continent, but they didn’t replace the original humans, who also evolved and diversified without mixing with the northerners. The southern groups maintained their isolation by adapting to extreme desert or deep jungle. We know their descendants today as the Bushmen, or Khoisan, and Pygmies. They have lighter skin and straighter hair than the northerners, among other differences. Later, one of the northern groups migrated out of Africa; these migrated and diversified further, eventually peopling the whole world.

Recently, on a photo safari in Botswana, as we talked about human diversity, our guide—a Motswana man who spoke Setswana in the Niger-Congo language group, which also includes the Bantu languages—seemed a little surprised and even sceptical when I mentioned that, genetically, he and I were more closely related to each other than either of us are to his wife, a Khoisan. That is what the recent genetic results mean: at the highest level of genetic diversity, there are two kinds of people in the world: the Khoisan/Pygmy group, and everyone else. At the highest level of unity, there is one kind: modern humans. In between is a multitude of genetic, cultural, and ethnic diversity at different degrees of separation. So what are we to make of designations like “Black” and “visible minority”? Visible to whom?
Fortunately, all is not lost. Language evolves along with genetic heritage, and culture tracks language, so it is actually possible to modify our terminology to celebrate both our diversity and our unity. We can start by eliminating confusing terms related to appearance, by reserving country designations for political discussions, and by using genetically and linguistically accurate terms for ethnic groups.

Another piece of the Atlantic Rainforest falls

Someone forwarded to me a video about Ford Motor Co.'s new, modern manufacturing plant in Brazil with a comment about globalization and what it means for American workers, but what caught my eys was the statement: “...amid the remnants of the Atlantic Rainforest...”. This is one of the world’s top 25 “biodiversity hotspots,” one of the most biodiverse ecosystems and most endangered and it’s just about gone. It hosts a huge number of species that occur nowhere else, including several monkey species. I have photo of two species, the Golden-headed Tamarin shown above, and others posted at http://picasaweb.google.ca/Lee.Coquitlam/Primates# that I took in the Lisbon Zoo. By 2003 the Atlantic Forest was down to about 5% of its original area (around 70,000 km2) and shrinking fast. It has (or had) 261 species of mammals, 73 of which occur no where else in the world. Species are still being discovered there, but it seems that it is being destroyed so fast that many of its species will be lost before they are ever “discovered” by scientists—although the local people who eat them know that they are there! I guess when they are gone, we can thank Ford for their small part in this environmental catastrophe.


I’ve never been there. Maybe I will one day, but I'd better hurry or it will be gone.

Globalization is bad, not just because it engenders poverty in the already-poor while enriching the already-rich. What it means for the environment is that as long as any country has resources left, another country will buy them, in many cases from the politicians and their friends, leaving their own people without productive land and resources. The economies of the rich countries can run as long as there are resources somewhere that they can buy, but every year fewer countries have resources left for sale, or for domestic use. The politicians haven’t noticed that the global economy has transitioned from one of producing countries competing for buyers for their resources, to consuming countries competing for access to dwindling resources. Meanwhile, the countries with no more resources for sale or local use often become “failed states” and a strategic threat to the interests of countries like the USA and Canada. It can’t last forever.

Self-awareness in humans and mammals: predators and prey

I just read Richard Leakey's 1992 book, Origins Reconsidered. He talks about self-awareness as being one of the hall-marks of human cognition, and it’s demonstrated by deception—if you can think to deceive someone, you must be able to imagine what he/she is thinking and how he/she will react to your own actions. The development of this went along with transitioning to a hunter-gatherer society. I remembered hunting (formerly with a rifle, now with a camera) and recalled how every hunter, when in sight of the quarry, will look away and pretend not to notice the quarry, while working closer enough for a shot. Especially, we never make eye contact with our prey. This is universal hunting behaviour. It seems innate: so obvious that it doesn’t have to be taught. Then I thought, wait a minute: the prey must have some self-awareness to observe the hunter and decide whether its intentions are dangerous or not.
One can extend this in many directions, e.g.: (1) On my morning walks, when I pass a house with a dog on the porch, if I don’t seem to notice it, it watches me casually, briefly, and then looks away. But if I stop and look directly at it, first I see the hackles rise, and within a second or two it’s on its feet in an agonistic posture, or barking. (2) I have a photo of 27 mature bighorn sheep rams sunning in a steep meadow and not one is looking directly at any of the others. I had read Val Geist’s book and easily recognized this confrontation-avoidance tactic. (3) Sheep “present horns” to each other during male-male competitions: one stands broadside and holds his head so his opponent can see the size of his curl. Once when I came upon a Dall sheep ram in the Yukon, at first I looked studiously away and pretended not to notice him, so I could get closer for a photo. But the terrain prevented a close approach, so I made myself into a threatening ram by holding my arm up beside my head in a curl, broadside to the ram, and he instantly reacted assertively, strutting back and forth presenting me his horns, and coming closer and closer until I decided that was close enough and took the photo—whereupon he went back to grazing. So in this case, I was humanly deceiving him and he was bovinely reacting, but he must have had some sort of self-awareness to determine my changing states of attention (and intention) towards him.
How many wildlife films have we seen of a wolf among caribou, or a lion among wildebeest, pretending to ignore them while the prey watch intently to try to determine their intentions? Are these hunters not practicing deception?
Probably Leaky could explain this, but didn’t go into the nuances because of space limitation, and to not bore his audience. When I get a minute, I'll look into the literature.

Reptile Friendships

I'm sure that reptiles haven't been studied socially enough to make any statements about their social behaviour repertoir, but I think they form "friendships" like mammals and birds. This is because our son Andrew had a variety of lizards for several years and it was easy to see that they were comfortable with him and with each other, and to a lesser extent with the rest of us. If the lizards happened to be loose (he often let them out to roam around), upon entry of a strange human or reptile or dog, they would flee to Andrew and run up his body and cringe hiding on the side of his head that was away from the stranger. He often suffered multiple scratches from their sharp claws when a strange visitor would reach out to try to touch or pet the reptile. They didn't flee to a dark corner or to their terrarium; they chose Andrew. Well, it doesn't prove anything, except that reptiles are a lot more perceptive of individuals than we give them credit for, and can differentiate between known "friends" and strangers who are obviously potential foes.

The Jordan Tourists Never See 5: Burqu'

Leaving at dawn from a research station in the eastern desert, about 140 km east from Azraq on the straight highway to Baghdad, we passed through the village of Safawi, where we filled our water and gasoline containers and bought groceries for lunch. After another 90 km we passed a military checkpoint, Muqat--but no town--about 50 km before the Iraq border. The desert was flat and featureless and the 4 x 4 droned on. After hours of this, Hannah was absently watching miles of nothing pass by, listening to Lebanese music on the radio while Dr. Saad, an ecologist, and I chatted about our project (see December 31, 2009 post: Trek of the Al Kuwaiti). Suddenly Dr. Saad braked, turned off the pavement and began driving in the soft sand perpendicular to the highway. This got Hannah's attention: There was no road. "What...?" she asked, not a little dismayed.

"We have no further need of roads," I said, grinning. "This is the way to Burqu'."

I had been to Burqu’ before, but it was Hannah’s first time. Burqu’ is astonishing, not so much for the Roman/Byzantine/Islamic fortress, or even the lake, but for where it is. It is the only permanent water supply south of Syria, west of Iraq, north of Saudia Arabia, and east of Azraq Oasis (see my January 6 note on Azraq). The Bedu (Bedouins) have watered thelr livestock there since ancient times. Nabateans (no, their culture was not limited to Petra, as you might gather from the tourist literature there) had created the lake by damming a permanent spring around 300 BCE (Before the Common Era). Later, the Romans built a "castle" fortress to house a garrison, one of the most remote of their realm. Still later, Byzantine monks used it as a monastery. In 700 CE the Caliph’s son, Prince Al-Walid, built a wall enclosing the castle in a courtyard. On its walls are Roman and Kufic (an early form of Arabic) inscriptions. Throughout recorded history, Bedouin tribes have fought over it and travelling caravans stopped there to water their camels. In recent years, the government enlarged the pond into a reservoir by building a new dam further along the wadi.

Burqu' is as important to wildlife as to people. Being the only water source in a vast stretch of the great Syrian Desert, it is a crucial stopover for migrating waterfowl, shorebirds and raptors. For all the birds migrating between Eurasia and Africa, there are only two routes: one down the Jordan Valley and across the northern end of the Red Sea, and the other across the Syrian Desert and across the southern end of the Red Sea. They need water, and Burq'u is the only source for hundreds of kilometers. In winter and during migration, Burqu’ hosts millions of birds of more than 200 species. It is one of the Middle East’s most important sites for raptors, and the basalt desert surrounding it is also the last refuge for gazelles, small mammals such as hares, jerboas and girbils, and a considerable diversity of predators: red fox (Vulpes vulpes), sand cat (Felis margarita) Syrian jackal (Canis aureus syriaca), Arabian wolf (Canis lupus arabs), Ruepelli’s sand fox (Vulpes rueppelli), caracal (Caracal caracal), wild cat (Felis sylvestris tristrami), and Syrian hyaena (Hyaena hyaena syriaca) have been detected there in recent surveys.

Dr. Saad continued navigating the trackless desert. After a while, Hannah said, “I see the oasis!” Our colleague smiled conspiratorially, leaving it to me to tell her that it was only a mirage. After another hour, we crossed a rise and saw an eight metre tall black castle looming over a 2 km long lake. Flocks of ducks and shorebirds flew up, watched intently by hawks and eagles—I counted five species—while hoopoes, larks, wheatears, warblers, flycatchers and other birds sang among the bushes. A shepherd watched her sheep grazing in a grassy meadow on the far side. Hannah waited a moment before saying, “Okay, that’s not a mirage.”

The rough surrounding terrain limits hunting, providing a natural refuge for rare wildlife. A 700 km2 nature reserve is proposed. If Arabian oryx, Persian onagers, blue-necked ostriches, and cheetahs are ever reintroduced to Jordan, it will be here.

Book Review: The social behaviour of older animals

Before Diane Fossey, even before Jane Goodall, there was Anne Innis Dagg. Anne went to Africa in 1956 to study wildlife, possibly the first foreigner of either gender to do so, except for colonialists who were posted there. She earned her PhD studying the gaits of large mammals, including the giraffe, and had a raft of publications, including the giraffe species account in Mammalian Species (the apex achievement, for a mammalogist), and books that are still the definitive references on giraffe and camels. She became an expert on mammalian (mainly ungulate) locomotion and gaits. In 1973 she and a female colleague set off with a guide and camel driver into the Sahara (it was no safer then than now!) to study camels and their books and papers are still key references. As sort of a sideline to her research and teaching, she began challenging gender bias in biology – and who better to do so than one who had to masquerade as a man just to be accepted onto the property of a South African farmer whose wild giraffe population would be the focus of her first study? In scholarly articles and books, she destroyed gender stereotypes and challenged sociobiological theories (for example, that lion and leaf monkey males always kill young that are not their own so they can have sex with their mothers and pass on their genes; and females living past reproductive age are a useless drain on resources and contrary to evolutionary theory).

“The social behaviour of older animals” (The Johns Hopkins University Press, Baltimore: 2009) is scholarly (and should be on the reading list of every biology student), but written in a very readable style accessible to the lay public. In it, she explores the contributions of older, and especially post-reproductive, animals to their families and societies in an evolutionary context. She shows why, for a wide range of animals, but concentrating on mammals and especially primates, the resources consumed by post-reproductive males and females are more than balanced by their roles as teachers, leaders and mediators; and how their knowledge and wisdom increase the survival chances of their families and societies.

Dagg and other researchers have largely dispelled the ideas of the sociobiologists (although many don't know it yet), which define human behaviour in terms of self-interest. Selfishness is only part (and often wrong, at that) of a much broader view that is not yet in focus. The overthrow of sociobiology has left a sort of vacuum in our understanding of us, from which a new paradigm must soon emerge. Biologists are beginning to explore the evolutionary basis for such human qualities (I'm not saying they are exclusively human) as altruism, compassion, ethical behaviour, moral values, and appreciation of art and beautify in all of its forms. Their results will be most enlightening.

Selected books and key papers by Anne Innes Dagg

Dagg, A. I. 1971. Giraffa camelopardalis. Mammalian Species 5:1-8.
Dagg, A. I. 1973. Gaits in mammals. Mammal Review 3:135-154.
DAGG AI and JB Foster (1976): The Giraffe: Its Biology, Behavior and Ecology. Van Nostrand Reinhold, New York
Gauthier-Pilters, H., and A. I. Dagg. 1981. The camel. Its evolution, ecology, behavior, and relationship to man. The University of Chicago Press, Chicago.
Dagg, A. I. 1978. Camel quest: summer research on the Saharan camel. Otter Press, Waterloo, Ontario.
Dagg, A. I. 1983. Harems and other horrors: sexual bias in behavioral biology. Otter Press, Waterloo, Ontario.
Dagg, A. I. 1998. Infanticide by male lions hypothesis: A fallacy influencing research into human behavior. American Anthropologist 100:940-950.
Dagg, A. I. 2000. The Infanticide Hypothesis: A Response to the Response. American Anthropologist 102:831-834.
Dagg, A. I. 2005. Love of shopping is not a gene: problems with Darwinian psychology. Black Rose Books, Montreal.
Dagg, A. I. 2006. Pursuing giraffe: a 1950s adventure. Wilfrid Laurier University Press, Waterloo, Ontario.
Dagg, A. I. 2009. The social behavior of older animals. The Johns Hopkins University Press, Baltimore.