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The origin of the human family

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Matt Walker Matt Walker | 15:45 UK time, Tuesday, 13 December 2011

Vintage family from England

An English family from days gone by

Celebrating Christmas is often a family affair.

Nan and Granddad, Mum, Dad and the kids, perhaps Uncle Charlie dropping by.

It’s an ordinary scene. But perhaps it’s one that is too familiar, that we never question.

Because have you ever wondered where the human family actually came from?

New research into primate societies is helping to answer that very question; shedding light on the origins of the human family.

The work attempts to explain how the family unit evolved, and why humans have different family structures to our closest relatives, the other great apes.

Although human families seem terribly normal to us, the human family unit is, biological speaking, very novel.

Herds and flocks

All animals have a biological heritage; a biological parent if they reproduce asexually or two if they reproduce sexually, and commonly siblings to which they are genetically related.

But most animals don’t live with their parents or siblings; animals that hatch from eggs often never meet their parents, and many that are raised by their mother never know their father.

Fewer still are raised by both biological parents, in the company of their siblings.

And even fewer of those have segregated family units like we humans do, living in families into which only the closest relatives are invited.

Most animals either live alone, or spend their days with half-siblings, uncles, cousins, cousins many times removed or a herd or flock of genetic strangers.

There are many types of human family, involving step-parents, foster parents, adopted parents and children, half-siblings and same-sex couples, but we generally stick to small tightly-bonded nuclear family groups.

Gorillas

Can we see a little of ourselves in a gorilla family? (photolibrary.com)

Two researchers in Japan are now trying to identify what drove the evolution of our family behaviour.

Wataru Nakahashi and Shiro Horiuchi of the Meiji Institute for Advanced Study of Mathematical Sciences in Tamaku, Kawasaki have taken a theoretical approach, due to the general lack of early human fossils and artefacts that might explain why early humans lived as they did.

Killer fathers 

They created mathematical models that might predict or explain the mating and grouping strategies that might emerge among certain groups of primates facing certain conditions.

Many modern primates have followed a particular path, for example. In species such as baboons, males have large canines and compete with one another, often forming coalitions to oust rivals. Such males may kill offspring that are not their own, in a bid to make females more receptive to mating. In these societies, females may evolve promiscuous behaviour, to cloud the identity of their offspring and prevent such attacks.

Humans, and some other primate species, have taken a different path.

On a societal level humans generally form groups with multiple males and females. Within these, smaller human groups uniquely tend to be founded on exclusive, long-term sexual relationships, usually between a male and female (Mum and Dad), and each is prohibited from having sexual relationships outside the family (having affairs with all the neighbours for example). Once these ties are made, males tend not to compete strongly with one another (Dad fighting with another dad down the street over who should be with Mum), and females are not promiscuous (Mum having multiple affairs).

Australopithecus

Australopithecines liked the family life

Now affairs do of course happen, men fight and families break up – but in a general biological sense, humans have evolved a pretty stable and consistent system of family units in which we survive and rear offspring.

The fossil record suggests that humans developed their own family system a long time ago, as early hominids, evidenced by the discovery of family groups of Australopithecines for example.

But while we might know roughly when it arose, we do not know why it did. 

Measuring promiscuousness

To investigate, Drs Nakahashi and Horiuchi started by taking the mating systems of different ape species. 

Gibbons form groups of a single male and female with offspring, with each pair monopolising territory. Orangutans live alone, with males mating with multiple females that wander into their territory. Chimps form promiscuous groups involving many males and females, while gorillas live in cohesive groups that usually include one mating male and many females.

Dr Nakahashi and Dr Horiuchi then mathematically modelled the conditions required for each system to emerge, and become stable, taking into account variables such as male and female strategies, group sizes, reproductive rates, and average promiscuousness among males and females. 

They found that the human family system was much more likely to have evolved from a gorilla-type system, rather than a chimp-type system.

The most plausible scenario, and that which best fits the scant fossil evidence, is this:

The last common ancestor of humans, chimps and gorillas had a body similar in size to modern gorillas.

Victorian family (Getty images)

A Victorian family (Getty images)

That ancestor also had a mating system similar to the gorilla.

Then the climate in Africa became drier, the scientists write in the Journal of Theoretical Biology.

Those apes that were the ancestors of modern gorillas maintained their size by eating a lot of fibrous plants. And because they were big they were not predated on as much by big cats. That lack of predation pressure allowed proto-gorillas to maintain their group structures and mating systems: a gorilla-type family if you will.

The ancestors of chimps and humans though evolved smaller bodies as the climate dried. Crucially that made them more vulnerable to predators. To compensate, and to protect themselves, they started ganging together, forming groups with multiple males.

Here though, humans and chimps moved apart.

Swapping partners

The mathematical models suggest that a human-type family, and a chimp-type family, are both stable strategies. And quite small changes could have forced humans toward forming small nuclear family units and chimps into large, promiscuous units.

It is unclear what those changes might have been, but it may have been the environment in which both early apes lived, with proto-chimps living in forests, eating a certain diet and proto-humans taking to the savannah, feeding on another.

Orang utan family

Orang utans do it differently

The maths behind the hypothesis is complex, and the summary above necessarily simplistic. But hopefully you get the idea.

Many people can find the human family unit a difficult, tension-riddled thing, as relatives are forced together and struggle to get on. Christmas if often defined by family rows as much as family gifts.

But the human family unit is also an immensely powerful thing.

In humans, the family system allows groups to exchange males and females, and gain new mating partners, without aggressively competing for them.

That exchange of partners might have allowed human groups to start to collaborate rather than compete with one another.

Such cooperation might have been the building blocks of human society, which differs dramatically from other primates.

And, the maths suggests, it all might have started with a bit of proto-gorilla loving.

Comments

  • Comment number 1.

    My personal view is as human beings evolved and learned to communicate by language, from then on rules where made and whether these were cloaked in a religious way or law abiding way it has happened to be that humans live generally in a nuclear family because it works, and works well.. However, ther are examples where h.beings live like gorillas, with males having more than one female within his family and that is 'tolerated' in society too, and seems to work for those who follow this route.

  • Comment number 2.

    This is a decidedly rose-coloured view.
    To suggest that humans are "not promiscuous" due to some sort of rules we've set up is absurd.
    Humans are quite promiscuous. When we look at the religiously devout, who presumably endorse every single one of the tenets of their religion, including those against promiscuity, what do we see? Widespread promiscuity.
    What I believe exists is a continuous tension between the "rules" a society has promulgated, with open or secret defiance of those rules. The question is, what is the penalty for defying those rules, and this is not evenly distributed. There are those who by their good looks, affability, political position, can pull off an occasional or even frequent deviation from such social rules, and get away with it. Look at the whole DSK scandal. He's now portrayed as a victim, and look at his wife's reaction all along.

  • Comment number 3.

    Interesting stuff. I'm a speech scientist, and for me, the characteristics of human speech clearly evolved for face to face communication between mature individuals, not mating purposes, so the evolution of the human family unit is for me intimately tied up with our most human characteristic: speech. Nice to see an attempt being made to work out how (and when!) that unit came into being.

  • Comment number 4.

    For the author to throw out the chimpanzee descent of the Recent Out of Africa model is correct. (Along with throwing out everything else in that flagrantly political and not scientific construction.)

    But the actual replacement is not another African ape. It is rather a very messy and regionally-uneven human ancestry going back likely 12-15 million years to a number of different great ape species in Eurasia and Africa.

    We can see at least several millions of years of mixing in the Homo floresiensis "Hobbit" specimen from Indonesia. It clearly has Australopithecine, Homo erectus, and Homo sapiens characteristics.

    Likewise the tooth of the new Denisova species, proven to have interbred with recent humans only 30,000 years ago, exactly matches the morphology of 2-4 million year old Australopithecines. That is if you look at the tooth analysis chart hidden behind the pay-wall in the original Nature Magazine publication, rather than the open fraud against science being promulgated in the press.

    And when the human male Y-chromosome was finally sequenced in full recently, it turned out it looks nothing like the chimpanzee Y-chromosome. We're probably chimp in the direct female line, and descended from an orangutan-like European ape (possibly the new Anoiapithecus brevirostris) in the direct male line.

    You'll also notice that humans have A-B-O blood types, which are found separately in different great ape branches.

    Now the article mentions, but then doesn't follow up on, gibbons already living in nuclear families. And it forgets to mention all the obvious non-nuclear traditional human societies like harems in the Middle East, and matriarchal societies where women divorce their husbands and take up with new men easily.

    So diversity in human family structures. Inherited from diversity in human ancestry. Harems likely come from the Neanderthals. And the rude meaning of "fairy" comes from the actual fairies -- the species like the Denisovans and "Hobbit" that were living in the woods all around the Old World until getting interbred with, and turned into bigger folk, as recently as the forests in Ireland getting chopped down.

  • Comment number 5.

    One unique aspect of humans is the absrnce of rutting. Bipedal gait prevents the usual swelling of the vagina, so it seems reasonable to think this trait goes way back. Men don't know whzen it's worth fighting to mate, women get to choose; that seems to me the basis of our evolution

  • Comment number 6.

    This article is not very inclusive of BLACK families WHY ?
    No family pictures of BLACK or Asians WHY ?

  • Comment number 7.

    This article is deeply flawed. Nuclear families are not the most common sort of family. In the recent past, they have been, in our culture. Extended families were always the norm worldwide, and here before the nuclear family took its temporary hold. We could look at the cultural changes that led the nuclear family to come in and out of fashion, or we could look at the evolutionary changes between our human extended families and those of other apes, but claiming that the human family is the nuclear family is patently untrue.

    I suppose this is what happens when people study science but not history.

  • Comment number 8.

    I suggest that early man(being more intelligent perhaps) recognised that by living in family groups it clearly defined which creatures belong to the same gene pool making it easier to seek partners from outside the same family and avoiding inbreeding- whether they recognised this for what it is or instinct is questionable, it favoured the regeneration of healthy offspring. It was probably a matriarchal society.

  • Comment number 9.

    The strategy adopted (in socio-biological terms) by hominids is quite distinct. The species has invested, as a highly successful strategy, in a strong sense of the extended family group with nuclear units within this structure. The exceptions...harems etc and polygamy, polyandry are aberrant to the development, occuring in specific locales under specific circumstances.

    The tested economic base for milennia was and is the extended family....the ultimate social security system with its strong rules and metaphoric power....religion sanctioning rules for the common good (and survival) of the individual.

    The 'modern' isolate mode of the nuclear family or single parent family of the developed world is very recent and is still an experiment. It depends on the 'affluence' of the society and the 'specialisation' that the affluent society affords.

    It is a mere 100 years old and is still very much at the 'testing stage'.

    Its success remains to be seen.

  • Comment number 10.

    I have noticed in the garden that a few months ago there was one squirrel and now there are four who always seem to arrive together but do seem to fight with each other as well and are very defensive of each others food supply. I am not quite sure which are male and female and so cannot comment on whether it is the male of the species who is more dominant. It is interesting to note that they all seem to gang up together if the magpie arrives or the next door cat.

    I have created a log of all these activities in the hope that after a year I may well see a pattern. If anyone is able to shed any light on the squirrel behaviour I would be interested to know or if anyone can tell me the sex of my squirrels from my photos even better. www.thruthespyglass.blogspot.com

    ta

  • Comment number 11.

    My wiew fits with the article. However, I think tool making may have aided in the sharing of mates. If one or more bigger early human was keeping the females to himself, this might change when they start making tools. Then the bigger males might be more willing to share or run the risk of getting clubed in the back of the head by a smaller male.
    Some say that tool making may have led to the development of larger brains, but it could also have led to being more willing to share females as well as other things like food.
    With more having tools there would be more reason for equality and a sharing of resources. Even females could use clubs to encourage their right to have a say in who they mated with.
    As the clubs became more refined into different types of tools including axes, spears and knives the more equal the individuals who used them. Then each individual might start to recognize exclusive rights to a specific mate and less random mating and better identification of which child belonged to which male.
    A survey of human mating rituals among primative tribes around the earth shows a lot of variety, but all I have read about had developed some type of exclusive mating where mates recognized each other and their offspring.
    As for tool use even Chimps and other apes use different things in a tool like fashion and Chimps have been seen clubing other animals to death. It is not unlikely that early near humans did the same for defense and to get food.

  • Comment number 12.

    The information provided by John_D2 about "fairy ancestors" fascinates me. When I spent 2 years in Ghana in the early 60's, I discovered a belief in small red people living in the forests, thought by my Ghanaian friends to be mythical, and to have their feet attached backward. To my delight I learned when reading "Africa Dances," a 1935 travelogue written by Geoffry Gorer, that he had visited a village of small red people, in Ghana, North of the coast. Their apparent descendents, known for their "palm oil" hair (very dark red colored), are not uncommon in Accra.

  • Comment number 13.

    Modern day humans do not need to wander around in large "herds or packs" for protection, I don't need to take 20 other males to buy a bag of chips when I'm hungry and so it follows that the amount of mouths I have to feed is smaller. I only need to provide for my family, not the entire street, which is where I believe the family unit has it's origins.

  • Comment number 14.

    We humans, it seems to me, have but two major characteristics that distinguish us from the other mammals - the power of complicated speech (except perhaps in certain areas of places like Glasgow) and a uniquely awful capacity for violence. Most mammals will not fight one another to the death, whereas we do it almost as a matter of course, for sometimes quite trivial reasons.

    Next, all male mammals compete for the privilege of a mate; a competition that is often fiercely physical but, in outcome, very rarely lethal among other species. But with us, with our propensity to kill?

    It is not difficult to imagine, therefore, given our extreme homicidal tendencies (as evidenced by the fossil record as well as by the likes of Sylvester Stallone), that we have had to evolve a pattern of sexually stable relationships within the hunter-gatherer group simply to avoid the problem of our young men battering one another, and their elders, to death for the sake of a quick roll in the hay. In addition, these relationships had to be more or less monogamous so that every - otherwise potentially violent - male would be soothed by the regular attentions of his chosen sweetie. (The article itself alludes to this when it says, “Dad fighting with another dad down the street over who should be with Mum.”)

    This, I suggest, is the true origin of the hominid nuclear family which is not, as many suppose, a recent aberration, because it can be seen directly today in those few societies that have changed little in the last thousand or so years, and also indirectly in the fossil record.

  • Comment number 15.

    This is an afterthought and a bit off-topic, but I find myself intensely irritated by the comment at no.6 - “This article is not very inclusive of BLACK families WHY ? ...”

    My fiancée is African. She is NOT black; she is a delightful and uniform shade of milk chocolate. I am European. I am NOT white; I am a blotchy mixture of pink and brown, sun-tanned patches, streaked with bluish veins. Her skin is deliciously, silkily smooth, almost entirely devoid of hair - she has no need to shave her armpits, legs, or indeed anywhere else in order to improve her sex appeal. I am covered in unsightly tufts and layers of fluff, and I have to shave every day.

    Can we please all dispense with our dreadful habit of classifying each other by using wildly inaccurate descriptions of the colour and nature of our epidermis. We are Africans, Europeans, Asians, etc., or, more localised, I am English and my fiancée is Tswana.

    As for the illustrations in this article, yes, it might have been more appropriate to have used photos of, say, Aboriginal families from Australia or the Andaman Islands, but hey, give us a break - we’re all humans.

  • Comment number 16.

    All this is such a bizarre theory, assumption, guess work, it is made up rubbish. Humans evolving from Apes, whichever ape is nonsense. Yes, I believe in creation, before anyone asks. People often dismiss the Bible as a fable or a storybook, which is an opinion that some have, right or wrong it's an opinion. This article and these comments assume fact when no fact is proven beyond doubt. The same rules that the scientific community apply to ridicule the Bible do not seem to apply to their own vastly exaggerated claims.

  • Comment number 17.

    Well, ‘Sax’, yours is certainly an interesting point of view that one gathers - sadly - is shared by more than half of all US citizens and doubtless by many millions/billions of other people. What makes one even sadder is that this acme of divine creation - us - has turned out to be the most aggressive, dangerous, vicious and destructive species yet to have graced this otherwise fair and beautiful planet. Your mate, the Old Man with the long white beard, must therefore be, one feels sure, deeply dissatisfied with the dismal outcome of His efforts, which perhaps explains why there are worrying signs that He is intent on wiping the current slate of life clean and starting again with a new and better set of ‘intelligent designs’. In this noble endeavour I feel we should all, with due humility, wish Him the very best of luck. Practice, as they so rightly say, makes perfect.

  • Comment number 18.

    The model of a gorilla-type group, with one male and several females, would explain the diversity of human groups. Many human tribes, nations, etc claim descent from one man and his women. The Hellenes [Greeks] claim descent from a man named Hellen. Similarly, the Israelis from Israel, the Arabs from Ishmael, the Ionian Greeks from Ion.
    If these men differed in physical appearance , their descendants would each partly resemble the common ancestor, forming a tribe, then nation, then race. Are all the Chinese-type races descended from a common ancestor?

  • Comment number 19.

    Gosh, but there are some fascinating theories surfacing on this blog! The impeccable logic, ‘IABA’, of your novel take on human evolution is quite breathtaking. The various patriarchs you mention must doubtless have each had a huge horde of variegated females at their disposal (more perhaps even than your average gorilla) because had they not, all Arabs, say, would look much the same, which clearly they don’t.

    I also find your question about the various Chinesie types to be most engaging. Obviously Ho Chi Minh, a thin little squit of a fellow, cannot possibly have descended from the same patriarch as the robust and corpulent Mao Tse Tung. However, you may be interested to know that recent genetic research has linked a startlingly high proportion of Central Asians to the loins of Genghis Khan, though personally, given his fearsome reputation, I would have hesitated to call him a gorilla to his face.

    The racial group you omit to mention, a tad surprisingly, is that of the Africans. They, I seem to remember, are descended from a chap called Ham. Given African dissimilarity from the rest of us, Ham and his females must have been very different from Hellen, Ion and the others. However, he at least didn’t need quite so many nubile and fecund young women as did his fellow patriarchs because Africans, as we know, almost exactly resemble each other.

 

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