What makes us human?

Jun 03, 2014 by Rob Brooks
Thomas Henry Huxley was a dynamic chalk-and-talk lecturer and a fabulous anatomist. Here he is lecturing on the anatomy of the gorilla skull. Credit: Wikimedia Commons

What separates humans from other animals, including our closest relatives? It's one of those big questions perennially posed by the evo-curious public. But until recently I seldom gave it much thought. Mostly because the answers tend to get hung up on one trait that differs from our closest great ape relatives: our upright stance, the shape of our toes, the size of our brains.

Millions of years of separate evolution has, of course, resulted in considerable divergence in all manner of traits. It makes no sense to elevate one particular one to some kind of special status - the one thing that makes humans … .

Questions about what separates us from other animals also carry some unfortunate baggage. The belief that there is something inherently special about humans and the way we arose is more suited to creation mythologies and religious doctrine than to a scientific, testable view of the world. The notion of special creation, and those perversions of evolutionary thinking that defend humans as exceptions, tend to come pre-fitted with taxonomic chauvinism of the following sort:

Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.

Victorian Clash of Minds

The shard of evolutionary thought that most gets under the skin of religion is the notion that humans are not created special, are not made in any divine image. Darwin's contemporary, the great anatomist Richard Owen, fiercely defended humanity's paragon status and the Victorian English status quo from transmutationalism (as evolutionary thought was then known) and the bestialisation of man.

This video is not supported by your browser at this time.
Professor Thomas Suddendorf talking at TEDxUQ about the evolution of human minds and some of the science he writes about in The Gap

When the first pelts and skulls of a large newly discovered 'indescribably fierce' African ape (the gorilla) sensationalised 1850's London, they piqued the curiosity of a working class then challenging ideas of human uniqueness and a divine social order. Owen lectured the British Association in 1854 that human brains bore special structures - such as the hippocampus minor - lacking in apes. Here, Owen claimed, lay the evidence for human uniqueness.

A young Thomas Henry Huxley located the gorilla's hippocampus minor (remember they were working with skulls) in March 1858 (months before the Darwin-Wallace paper on natural selection), showing himself the better anatomist. More important, Huxley's interpretation that chimps, gorillas and humans are at least as similar to one another as any is to baboons - now common knowledge - devastated Owen's claims to human uniqueness.

One by one, all claims to human uniqueness have similarly fallen aside. For example, in 1960 Jane Goodall, refuted the idea that human tool use set us apart from our closest relatives. Perhaps the entire enterprise of looking for traits that distinguish us from other apes is misguided and the differences are more quantitative than qualitative?

Mind the Gap

Last month I enjoyed the pleasure of discussing this topic with UQ's Professor Thomas Suddendorf at the Sydney Writers Festival. Suddendorf was at the festival to talk about his book The Gap: The science of what separates us from other animals (Basic Books) recently published to enthusiastic reviews.

The Gap tackles the difficult question of what separates humans from other animals, but part of its genius is the way it begins by putting humans into a biological context. Only by viewing humans as organisms can we begin to test the idea that humans differ from other organisms, and what those differences might be.

A psychologist, Suddendorf works with both human children and other primates to understand mental evolution and the development of those mental capacities in childhood. The Gap considers in detail the mental traits most likely to have effected the ecological success of humans relative to our great ape relatives. Where orangutans, gorillas and chimpanzees languish in ever-shrinking patches of rainforest, he points out, humans now make up more than seven times the biomass of all other wild mammals combined. Something sets us apart, ecologically at least, from our closest relatives.

After reviewing the current scientific evidence of human and ape capacities in the areas of language, (the capacity to imagine the past and the future), theory of mind, intelligence, culture and morality, Suddendorf arrives at the conclusion that across these domains, two major features set humans apart:

Our open-ended ability to imagine and reflect on different situations, and our deep-seated drive to link our scenario-building minds together.

That's as good an answer to the questions about human uniqueness as I have ever encountered. What is more, the answer, and Suddendorf's fascinating path to that answer has made the very question of human uniqueness interesting again.

Explore further: Human ancestor was less-chimp-like than thought: study

add to favorites email to friend print save as pdf

Related Stories

Scientists complete Bonobo genome

Jun 13, 2012

In a project led by the Max Planck Institute for Evolutionary Anthropology in Leipzig, an international team of scientists has completed the sequencing and analysis of the genome of the last great ape, the ...

The parasite that escaped out of Africa

Feb 21, 2014

An international team of scientists has traced the origin of Plasmodium vivax, the second-worst malaria parasite of humans, to Africa, according to a study published this week in Nature Communications. Until recentl ...

Recommended for you

Organismal biologists needed to interpret new trees of life

Jul 16, 2014

Rapidly accumulating data on the molecular sequences of animal genes are overturning some standard zoological narratives about how major animal groups evolved. The turmoil means that biologists should adopt guidelines to ...

User comments : 21

Adjust slider to filter visible comments by rank

Display comments: newest first

Torbjorn_Larsson_OM
5 / 5 (2) Jun 03, 2014
A testable hypothesis, perhaps. So let Suddendorf try.

I've heard four differences, which match our phylogeny rather than perceived differences:

1. Our small canines, coevolving with socialization. That is perhaps the only anatomical trait that distinguish hominids as clade.

2. Our precision thumb grip, coevolving with tool use.

3. Our mentor-adept learning, coevolving with tool use.

4. Our language, coevolving with tool use.

The 3 last are Homo (humans) specialities.
JVK
1 / 5 (6) Jun 03, 2014
"The existence of teleological laws means that certain physical outcomes "have a significantly higher probability than is entailed by the laws of physics alone—simply because they are on the path toward a certain outcome." http://www.nybook...on=false

Biophysical constraints prevent mutation-initiated natural selection and biodiversity correctly attributed to nutrient-dependent pheromone-controlled ecological adapatations, which are manifested in the behavioral and morphological phenotypes of species from microbes to man. Ecological, social, neurogenic, and socio-cognitive niche construction link food odors and pheromones to biodiversity via the conserved molecular mechanisms of amino acid substitutions that Dobzhansky (1964) noted 5 decades ago differentiate the cell types of other primates from humans. "...hemoglobin S differs from A in the substitution of just a single amino acid, valine in place of glutamic acid..."
JVK
1 / 5 (6) Jun 03, 2014
"If the materialist, neo-Darwinian orthodoxy contradicts common sense, then this is a mark against the orthodoxy, not against common sense. When a chain of reasoning leads us to deny the obvious, we should double-check the chain of reasoning before we give up on the obvious."

It is obvious to everyone except the supporters of neo-Darwinian theory that ecological variation leads to ecological adaptation via the conserved molecular mechanisms that link the epigenetic landscape to the physical landscape of DNA in the organized genomes of species from microbes to man.

"THIS MODEL DETAILS HOW CHEMICAL ECOLOGY DRIVES ADAPTIVE EVOLUTION"
http://www.ncbi.n...24693353

Others have since incorporated physics and chemistry so that "adaptive evolution" is no longer the appropriate term to use for what are clearly ecological adaptations. I apologize for any confusion caused by my prior use of the term 'evolution' instead of 'ecological adaptation.' The theorists made me do that!
JVK
1 / 5 (6) Jun 03, 2014
Re: "Huxley's interpretation that chimps, gorillas and humans are at least as similar to one another as any is to baboons - now common knowledge - devastated Owen's claims to human uniqueness."

"...scientists studying the mammalian brain should bear in mind that bees might be able to create complex mental maps despite having brains many times smaller than the hippocampus of a rat."

If the neurological basis of human cognition arises in the context of nutrient-dependent pheromone-controlled ecological adaptations, theorists should compare biological facts that link insects to elephants http://www.ncbi.n...8602213.

They should not keep pretending that the differences are more important than the conserved molecular mechanisms of biologically plausible cause and effect.

And someone should address the conflict between the speed of ecological adaptations in sticklebacks (500 species in 15,000 years) to what's claimed about millions of years of human evolution.
JVK
1 / 5 (6) Jun 03, 2014
"One by one, all claims to human uniqueness have similarly fallen aside."

Dobzhansky (1973) in Nothing in Biology Makes Any Sense Except in the Light of Evolution

1) "I am a creationist and an evolutionist."

2) "...the so-called alpha chains of hemoglobin have identical sequences of amino acids in man and the chimpanzee, but they differ in a single amino acid (out of 141) in the gorilla."

The mouse-to-human model now links a single base pair change to an amino acid substitution and hair color as well as human uniqueness in our receptor-mediated differences in teeth, sweat glands, hair and mammary tissue.

Hair color: http://www.scienc...0924.htm
Other differences: http://www.biotec...KfyhhstU
Captain Stumpy
4.3 / 5 (6) Jun 04, 2014
Biophysical constraints prevent mutation-initiated natural selection and biodiversity correctly attributed to nutrient-dependent pheromone-controlled ecological adapatations, which are manifested in the behavioral and morphological phenotypes of species
@jk
houston, we have a problem!
given that your model ALSO creates MUTATIONS, then the above statement is not only false, it is completely non-sensical. regarding your model of nutrient dependent p-controlled BS: I asked
DOES your model make any changes to the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element?
This is a yes or no answer
(this is the DEFINITION of Mutation) to which you answered
YES!
--Thanks for asking
so we KNOW that your model creates mutations... and now you are here arguing that mutations are not possible and your "model" is the answer, which means that either you are severely mentally incapacitated or you are being blatantly stupid.

or both
Vietvet
3.4 / 5 (5) Jun 04, 2014
It has to be both.
JVK
1 / 5 (5) Jun 04, 2014
I don't know any serious scientist who believes mutation-initiated natural selection and evolution could result in the integration of quantum physics into a model of optimised enzymes and biodiversity. However, I am familiar with works by Luca Turin "Molecular Vibration-Sensing Component in Human Olfaction" and by Michael Crawford "A quantum theory for the irreplaceable role of docosahexaenoic acid in neural cell signalling throughout evolution" that appear to properly place quantum physics into the context of an atoms to ecosystems model of nutrient-dependent pheromone-controlled ecological adaptations.

The atoms to ecosystems model also integrates what is known about seemingly futile cycles of thermodynamically controlled protein biosynthesis and degradation, which are required for organism-level thermoregulation in species from microbes to man. There was some discussion of "Genes without prominence: a reappraisal of the foundations of biology" in this regard.
Captain Stumpy
5 / 5 (5) Jun 05, 2014
I don't know any serious scientist who believes mutation-initiated natural selection and evolution
@jk
you continually attempt to promote yourself as a "serious scientist" and yet YOU BELIEVE in the above
your assumption that your model replaces evolution is hysterical at best, as your model is already a working part of evolution and continues to demonstrate mutations and how they can effect selection and create biodiversity
per your own admission (see above) your model creates mutations, therefore, AGAIN...
if you are stating that no real scientist or credible scientist believes in the above &
you empirically demonstrate it in your work (which supports evolution)

then you are attempting to undermine & discredit your own work which makes you either mentally deficient, blatantly stupid or (again) BOTH.

your words, not mine

anonymous_9001
5 / 5 (4) Jun 05, 2014
I don't know any serious scientist who believes mutation-initiated natural selection and evolution could result in the integration of quantum physics into a model of optimised enzymes and biodiversity.


This is worded incredibly oddly, but I'll try to decipher it. What suggests that mutation and natural selection are at odds with quantum physics and enzyme optimization? You're aware induced mutagenesis is a widely used tool for in vitro enzyme optimization I hope. Everything molecules do is based on their general and quantum physical properties. I'm not sure why you think they're ignored. There's an entire field dedicated to their integration: biophysics. I'm sure you've heard of it.
JVK
1 / 5 (5) Jun 05, 2014
Biophysical constraints that link ecological variation to ecological adaptations prevented by mutations but enabled by the nutrient-dependent pheromone-controlled physiology of reproduction are the central feature of my model which links sensory input to cell type differentiation in species from microbes to man.

For discussion of facts see: A Challenge to the Supremacy of DNA as the Genetic Material http://blogs.plos...aterial/

For a 5.5 minute video representation of my model, which refutes evolutionary theory, see: http://youtu.be/DbH_Rj9U524

Enzyme optimization is experience-dependent and links Luca Turin's works to the de novo creation of olfactory receptor genes via amino acid substitutions that differentiate structural and functional aspects of the cell types required for signal transmission. If not for academic suppression of Luca's insights, others who are not fools would have learned this more than a decade ago.
JVK
1 / 5 (5) Jun 05, 2014
I criticized Turin in a 2003 book review. http://human-natu...urr.html

"Turin never attempted to work within the system. Perhaps a future proponent of molecular vibration theory will manage better than Dyson, Wright and, most recently, Turin. Truly this theory may be years ahead of its time. It also may be a theory that cannot be sufficiently supported by scientific fact."

Luca politely told me that his attempts to work within the system had failed -- especially attempts that involved the Association of Chemoreception Sciences (AChemS). Two of my attempts to present have since been rejected and successful attempts have led to presentations that have been largely ignored. Dick Doty's book "The Great Pheromone Myth" led more people to deny established facts from across disciplines that link Luca's works to mine. http://www.amazon...0189347X

I now criticize AChemS. Luca and I did all that's expected of serious scientists.
antialias_physorg
5 / 5 (4) Jun 05, 2014
What separates humans from other animals

Why this need to separate 'us' from the rest? It's one of those nonsensical questions (like asking what is 'alive' and what is not. Both behave according to the same physical laws)

If we really must have an answer then just go with the answer to what separates any animal from the rest: The species barrier. (If it can't interbreed it's not the same species. This is scientific as it's testable)

Any other 'soft' criterium is just useless.
JVK
1 / 5 (5) Jun 05, 2014
Ecological variation enables ecological adaptations manifested as species-specific differences in morphological and behavioral phenotypes via the conserved molecular mechanisms that link physics, chemistry, and molecular biology in species from microbes to man.

Suddenly, the anonymous antialias_physorg notices this and suggests it is scientific and testable, as if I had not already detailed the experimental evidence in a series of published works since 1995, which culminated with publication last year of Nutrient-dependent/pheromone-controlled adaptive evolution: a model.
http://www.ncbi.n...24693353

My review was published on the same day as Nei's book: Mutation-Driven Evolution http://www.amazon...99661731 "...genomic conservation and constraint-breaking mutation is the ultimate source of all biological innovations and the enormous amount of biodiversity in this world." (p 199)

Did anyone mention that his book was full of pseudoscientific nonsense?
Captain Stumpy
5 / 5 (3) Jun 05, 2014
Did anyone mention that his book was full of pseudoscientific nonsense?
@jk
pseudoscientific nonsense would be a claim like this
I don't know any serious scientist who believes mutation-initiated natural selection and evolution
(YOUR WORDS, little guy!)

in fact... given that your own model creates mutations, then you continually make comments like above, then you can state with authority that: YOU PROMOTE PSEUDOSCIENCE NONSENSE

This would also support the evidence against your claims that WE are the idiots here, as it proves that you do not comprehend the basics of your own field.

check

JVK
1 / 5 (5) Jun 05, 2014
Functional associations among G protein-coupled neurotransmitter receptors in the human brain http://www.biomed...02/15/16

"...the apparent complexity of neurotransmitter signaling has an underlying global structure, which is not readily detectable if receptor interactions are studied in isolation."

That suggests errors made in theoretical representations of cause and effect that do not include experimental evidence of how olfactory/pheromonal input is directly linked to receptor-mediated behaviors via the nutrient-dependent de novo creation of G-protein coupled olfactory receptor genes. For example, human brain imaging links oxytocin to differences in monogamous and polygamous voles and to autism spectrum disorders with no consideration for the obvious role that olfaction plays in the behavioral phenotypes of the voles.

"But look -- we have a correlation" is the touted proclamation from researchers who then meaningfully interpret their meaningless results.
Egleton
1 / 5 (1) Jun 08, 2014
JVK
1 / 5 (3) Jun 08, 2014
Two articles: "Accessibility of microRNA binding sites in metastable RNA secondary structures in the presence of SNPs" http://bioinforma...abstract and "RNA editing and modifications of RNAs might have favoured the evolution of the triplet genetic code from an ennuplet code" http://www.scienc...14003208 address biophysical constraints that prevent mutations and natural selection from enabling the evolution of biodiversity. They place the evolution of biodiversity into its proper context of how ecological variation leads to ecological adaptations, which is what the Israeli school system has taught. They now will teach the theory of evolution so that their students can more clearly recognize the difference between pseudoscientific nonsense (i.e., evolutionary theory) and biologically plausible models. http://www.educat...olution/
Captain Stumpy
5 / 5 (2) Jun 08, 2014
http://www.scienc...14003208 address biophysical constraints that prevent mutations and natural selection from enabling the evolution of biodiversity.
@jk
well, there goes YOUR model jk!
They now will teach the theory of evolution so that their students can more clearly recognize the difference between pseudoscientific nonsense (i.e., evolutionary theory) and biologically plausible models
Uh, NOOOOO... the only thing your link shows is that RELIGION is once again tarnishing the ability for people to learn SCIENCE. I can understand WHY you would support that, as you attempt to support a RELIGION rather than science, but that is only your idiocy and your inability to comprehend your own work
PSEUDOSCIENCE is not recognizing that your own model causes mutations, and then arguing against mutations in science threads!
PSEUDOSCIENCE is posting articles that you misunderstand and dont support your religion while touting them as proof of your comments

IOW - YOU, jk
JVK
1 / 5 (3) Jun 08, 2014
http://www.scienc...9/supp/C
The articles in this issue on Neuromodulation each appear to support the atoms to ecosystems model detailed in Nutrient-dependent pheromone-controlled ecological adaptations: from atoms to ecosystems http://figshare.c...s/994281

Conserved molecular mechanisms establish the basis for 'conditions of life.'

Anyone who would still like to try to link the pseudoscientific nonsense of population genetics to a theory of how mutations and natural selection lead to the evolution of nutrient-dependent pheromone-controlled biodiversity, can compare the ridiculous beliefs about biologically-based cause and effect that they have incorporated into their theories to biological facts that have not changed since Darwin attested to them in the context of his 'conditions of life,' which were subsequently ignored as neo-Darwinism was invented.
Captain Stumpy
5 / 5 (2) Jun 09, 2014
Anyone who would still like to try to link the pseudoscientific nonsense of population genetics to a theory of how mutations and natural selection lead to the evolution
@jk
so what you are saying here is that you finally ADMIT that you are posting pseudoscience nonsense! thanks! after all, given that your model CREATES mutations, I still don't see WHY you keep fighting against mutations!

YOUR MODEL SUPPORTS THE EVOLUTION THEORY BY CAUSING MUTATIONS PER YOUR OWN WORDS

your continuing stance against "mutations" is only a stance against your own model, per your own words

Therefore logically we can only conclude that EITHER you don't know what you are talking about OR you are the idiot minion here

Personally, I think both apply

Check