Quadruped to biped . Not possible in terrestrial apes .

[Gerrard Farrell]

It has just struck me that the evolution of bipedalism among tree climbing /terrestrial apes is not really a feasible theory . This is because of the enormous disadvantage that a bipedal male is at ,compared to a quadruped of equal size , when it comes to fighting for mates/territory , unless weapons can be used decisively . I do not see anyway past this evolutionary problem for terrestrial quadrupeds to give rise to bipeds . Any thoughts ?

Here is an exert from a post of mine on podiatry arena -

"One of the major problems in moving from quadrupedalism to bipedalism is a greatly reduced ability to fight rival males unless weapons are used .

If you are a biped , it's a lot harder to get upright after a fall . Also ,if you are a naked bipedal male and an a quadruped with long fangs approaches , you have every right to feel very vulnerable .
Imagine standing in your birthday suit as an angry ,very large ( same weight as you ), pit bull ,runs at you looking for something to bite through !
Worse , imagine a pit bull with fangs and 2 pairs of grasping feet rather than paws .

Moving from quadruped to biped could not happen anywhere other than the tree tops .

Gerrard Farrell

Glasgow
scotfoot, 18 minutes ago

[Gerrard Farrell]

Re: Quadruped to biped . Not possible in terrestrial apes .

A good few years ago a paper was produced which claimed to illustrate why standing up to fight would give an advantage to a male with these characteristics when it came to sexual selection (D CARRIER 2001). It was suggested that this led to a commitment to bipedalism .
To my mind the paper demonstrated why a biped is at a huge DISADVANTAGE in a fight with a quadruped of the same weight .

If you look at the paper ( see link below ) ,which is open access , focus on figure 2 . Look at the target height for each of the two strike conditions , quadruped and biped . The standing target is raised to above the height of any attacking quadruped .
Although the standing position allows greater strike power to a lifted target it does not allow that strike power to be transmitted to a lower ( quadruped ) target . A standing position also makes it much harder to bite an opponent but makes it far easier for a quadruped opponent to inflict its own bites .

So great is the disadvantage , when it comes to fighting , that a quadruped ape could never evolve into a biped without an evolutionary excursion into the tree tops and brachiation .

Therefore , out go theories like seeing over grass ,radiation and overheating brains , food collection , standing to feed , etc . Terrestrial quadruped to biped ? Not a hope .

The Advantage of Standing Up to Fight and the Evolution of Habitual ...

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0019630

[Gerrard Farrell]

Re: Quadruped to biped . Not possible in terrestrial apes .

It is of course true that , like many other animals , knuckle walkers like chimpanzees adopt a bipedal crouch like position at the start of fights with their own kind .However ,as such fights progress the protagonists move frequently between an upright stance and a quadruped stance to avoid being overcome by the weight of their opponents ,pinned ,and bitten .


Obiligate bipeds do not have the quadruped stance option . If they are grounded ( knocked over ) they will find it very hard to regain their footing . I just cant see past this disadvantage unless weapons are brought into the equation .

[Gerrard Farrell]

Re: Quadruped to biped . Not possible in terrestrial apes .

So the title of this thread was "Quadruped to biped . Not possible in terrestrial apes " . But , on further reflexion ,perhaps it is . If you take fighting out of the equation , introduce sex for all and isolate your population from more agressive qaudrupeds , change towards a biped might be possible . A case in point would be the Bonobo . Interesting !

[Gerrard Farrell]

Re: Quadruped to biped . Not possible in terrestrial apes .

About 1.5 million years ago a last common ancestor gave rise to the ancestors of the modern day Bonobo (Pan Paniscus ) and Chimpanzee (Pan Troglodytes ) .

Bonobos are found south of the river Congo and Chimps to the north ,and some have speculated that it is the geographic separation of the two species by the Congo and one of its tributaries , that has allowed the Bonobo to evolve differently than the Chimpanzee .

But ,given time ,could you get from a Bonobo to a biped and would that process be similar to that which occurred 7 million years ago when a last common ancestor gave rise to Pan and Homo .

One mechanism by which a Bonobo might give rise to a habitual biped is as follows .

It is known that Bonobo society is dominated by females and that males displaying violent behavior towards females is prevented by female coalitions . Some have also forwarded the idea that alpha males in a group are selected not by males fighting each other for dominance but by female selection . It would appear therefore , that for a male to get ahead in Bonobo society ,they must have the goodwill of high ranking females . But if you are not the son of a high ranking female how do you ingratiate yourself with the decision makers ?

Well , favorable personality traits such as empathic behavior might boost your standing a bit , but the ability and willingness to provide females with a regular supply of meat is really going to make you popular . But how ?

Well let's say that through prolonged brachiation and perhaps a genetic mutation or two we get a Bonobo with long limbs , plenty of energy storing ligament and a pelvis that can be set at 60 or seventy degrees to the plane of the shoulders . ( Such an animal would be not unlike extant Gibbons in its ability to walk upright )

Now let's say our "tending towards upright" , hungry , Bonobo is confronted by a tree full of feeding/roosting birds . Every time it attempts to ventured near the base of the tree , the birds fly away . In frustration the Bonobo picks up an old broken femur bone which happens to be lying nearby and ,with the ability to stand upright and separate the plane of its shoulders from the plane of its pelvis ,and using both hands , it flings the bone ,at speed , up into the tree . And out falls a bird with a broken wing . Bingo

[Gerrard Farrell]

Re: Quadruped to biped . Not possible in terrestrial apes .

Let's say our Bonobo ,equipt with his newly discovered bird gathering ability ,becomes a big hit with the ladies and has many offspring . Might those offspring and their descendants become progressively better adapted to a two handed throw ( like swinging a baseball bat but letting go at the appropriate moment ) ,both physically and neurologically .

From the neurological perspective might subsequent generations ,given the nature of a full body throw aimed in a particular direction , develop genetically dictated left or right side dominance , not just for fine motor tasks but for also for more general tasks .

In effect , might we get the development of population handedness , were right/left side dominance affects not just the hand of choice for a task but also ,for example ,is linked to a dominant eye ?

[Gerrard Farrell]

Re: Quadruped to biped . Not possible in terrestrial apes .

From post #5 - " In frustration the Bonobo picks up an old broken femur bone which happens to be lying nearby "

Why an old femur bone and not a simple stick ? Well it has to do with physics and the effectiveness of a thrown hunting tool .

If you try and throw a stone using a two handed grip , it will leave your hands at the same speed as your hands were travelling at the moment of release . Let's say 10m/s .
An animal 20m away has 2 secs to get out of the way and only requires to move a short distance to do so . However ,if you throw a stick , the center of mass will be some distance from your hands at release and so moving faster (through a wider arc) . The thrown stick will therefore move towards the prey animal faster than the stone would , giving it less time to react . In addition the stick would be rotating about an offset center of mass giving a wider " hit area " and so a better chance of hitting the prey animal .

With a broken femur held at the broken end , the center of mass would be located close to the thickened , let's say distal , part of the bone . So even greater speed at release and an even wider " hit zone " as the bone rotates about the center of mass .

To recap then , perhaps 7 million years ago a Bonobo like animal evolved . Through brachiation and a female dominated society with less aggression , a trend towards longer limbs and a rotating trunk developed . Through trial and error , the Bonobo like animals found sticks ,naturally weighted at one end ,could be used for knocking birds out of trees .

Time passes ,the animals develop bodies better adapted to two handed throwing , and the size of prey animals increases .

It's not long before you get prey such as small ,thin legged antelope being driven by some hunters into the stick throwing range of hidden others , where such antelope are disabled and ultimately killed .

Looking back through this thread the most unlikely part of the story is the evolution of a female dominated ,bonobo like society ,from a chimp like last common ancestor . And yet it has happened in the Congo area .

Any thoughts ?

[Edmund Cramp]

Re: Quadruped to biped . Not possible in terrestrial apes .

I do find this conversation interesting, it makes me think and that's always entertaining - I thank you for this. But if evolution was influenced in the way discussed, why are there so few examples of bipedal animals? This is not an area that I would claim any serious knowledge of but when you look at the whole animal kingdom it seems to me that you could equally make the argument that bipedalism is an evolutionary dead-end as the vast majority of life is not bipedal and catches its next meal with limbs and teeth, not by throwing things. If the ability to throw solid objects was a benefit to survival then why is it so rare in the animal kingdom? On the other hand, the argument could be that bipedalism is so effective that we attack and eradicate any animal that attempted to invade our evolutionary space, but that would be a dead-end...

My feeling is that bipedalism has freed up the development of the hands, not to throw anything or hunt but to enable us to create and use tools and be more social and caring of other members of our species.

Edmund Cramp

[Gerrard Farrell]

Re: Quadruped to biped . Not possible in terrestrial apes .

Hi Edmund ,

Thanks for replying to the thread .
Quote

"My feeling is that bipedalism has freed up the development of the hands, not to throw anything or hunt but to enable us to create and use tools and be more social and caring of other members of our species."

No matter what twists and turns were involved in the eventual evolution of Homo Sapiens , my main interest in the subject is how bipedalism was select for in a group of knuckle walkers , which is what many believe our last common ancestor with the Genus Pan ,was .

It is not uncommon in nature to find animal species have a single trick or adaptation that other don't , and which has allowed them to flourish . For example the archer fish or the electric eel . I think it is quite plausible that the ability to throw sticks at high speed ( and speed is key here ) might have evolved in a "Bonobo like setting " and so added to a brachiation induced , and already existing , trend towards longer limbs and bipedalism .

Is there any evidence that the ability to throw sticks at high speed make a big difference to the viability of a hominin species ? Well it's simple enough to be within the compass of our distant ancestors but successful enough to still be in use today . For example , rabbit sticks were still used by humans , for life or death hunting purposes , until very recently (Native American Indians ,Aborigines) and might even have been the first valued possession among the earliest hominids .

Why are there not more stick throwing Hominin species around ? Neanderthals were around until about 40,00 years ago .It would appear our ancestors bred with some of them ( 2% of a modern Western Europeans DNA is Neanderthal in origin ) and out competed or killed off the rest . Sadly humans are quite capable of killing off a competing species . Capable even of genocide .

Are humans an evolutionary dead end . Until recently I thought we probably were but after reading a bit about the Bonobo perhaps there might be some hope . As women become more influential in the world , something that men instinctively resist , we might become more viable long term .

Sorry lads !