'Homo' is the only primate whose tooth size decreases as its brain size increases

Apr 03, 2014
Left: This image shows upper and lower views of cranium OH5 (Paranthropus boisei). Right: Same views of Homo sapiens cranium. Credit: UGR

Andalusian researchers, led by the University of Granada, have discovered a curious characteristic of the members of the human lineage, classed as the genus Homo: they are the only primates where, throughout their 2.5-million year history, the size of their teeth has decreased alongside the increase in their brain size.

The key to this phenomenon, which scientists call "evolutionary paradox", could be in how Homo's diet has evolved. Digestion starts first in the mouth and, so, teeth are essential in breaking food down into smaller pieces. Therefore, the normal scenario would be that, if the brain grows in size, and, hence, the body's metabolic needs, so should teeth.

However, in the case of Homo, this has not been the case, according to scientists in an article recently published in the journal BioMed Research International. The main author of the study, researcher Juan Manuel Jimenez Arenas, from the University of Granada's Department of Pre-History and Archaeology, points out that "This means that significant changes must have occurred in order to maintain this trend".

A change in diet, incorporating a higher amount of animal food, must have been one of the keys to this phenomenon. The quality leap in Homo's diet, through a greater intake in animal proteins, fats and certain olio-elements, is essential for a correct working and maintenance of the brain. On a similar note, a larger brain allows greater social and cultural development, which, at that time, led to the achievement of important technological innovations.

In order to validate this theory, the researchers evaluated the relationship between the size of post-canine teeth and the volume of the endocranium in a wide set of primates, among which were found the main representatives of Homo fossils. "Before we started the study, it was well known that, throughout the evolution of humans, tooth-size diminished and increased. We have established that they are two opposing evolutionary trends that have been linked for 2.5 million years, when our first ancestors within the Homo genus first appeared on the evolutionary stage".

Genetic Study

The study's authors also relate these changes to the inactivation of gene MYH16, linked to temporalis musculature, which fell in size approximately 2.4 million years ago. This would do away with an important barrier for encephalization (a hypertrophied temporalis musculature prevents the development of the cranial dome). Likewise, they analyzed their relationship with the inactivation of gene SRGAP2, which helps towards the evolution of the neo-cortex, playing a principal role in human development.

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RobertKarlStonjek
not rated yet Apr 03, 2014
The incisors DID keep increasing in size...so big, in fact, that they had to be hewn from stone and held in the hand...
JVK
1 / 5 (4) Apr 03, 2014
In the mouse-to-human model of ecological adaptation detailed in companion reports by Kamberov et al and by Grossman et al (2013), it became clear that a nutrient-dependent single base pair change led to an amino acid substitution and differences in a modern human population during the past ~30K years.

The differences in hair, teeth, skin and mammary tissue need only be linked via changes in the microRNA/messenger RNA balance and cell type differentiation in individuals of different species to see an example of how ecological variation rapidly leads to ecological adaptations via conserved molecular mechanisms in species from microbes to man.

Evolutionary theorists who insist on incorporating claims that ecological adaptations manifested in the human brain took 2.5-million years may need to learn more about the biophysical constraints that make mutation-driven evolution impossible.

http://www.socioa...53/27989
RVenu
5 / 5 (2) Apr 03, 2014
So, could have cooking started earlier than previously taught?
Squirrel
5 / 5 (1) Apr 04, 2014
The paper is open access: read it
http://www.hindaw.../406507/

On the Relationships of Postcanine Tooth Size with Dietary Quality and Brain Volume in Primates: Implications for Hominin Evolution
BioMed Research International
JVK
1 / 5 (4) Apr 04, 2014
"Specifically, we are interested in finding out where the more than 500 species of the Lake Victoria species flock originated from and what causes them to diverge so rapidly more than any other fish species in the same lake in a very short period of time (15,000 years)."

http://www.fishec...index_EN

Why have so few modern human species diverged in 2.5 million years, when 500 species of these fish diverged (e.g., in the same lake) in 15,000 years?
Anda
5 / 5 (3) Apr 05, 2014
These people are the world authority in Neanderthals. They are the researchers of the Atapuerca site, Altamira coves in Spain. Serious and smart people.

JKV: you know you don't make sense, I hope so, your polemic comment isn't even related to the article.
Anda
5 / 5 (5) Apr 05, 2014
JKV, google it before commenting, you'll learn something, and will appear smarter.
There were no "modern" human species 2,5 My ago and yes, they did diverge but later "only the strong survived".
I know, that means your ancestors too... sometimes evolution is weird
JVK
1 / 5 (4) Apr 05, 2014
JVK:
Why have so few modern human species diverged in 2.5 million years, when 500 species of these fish diverged (e.g., in the same lake) in 15,000 years?


Anda:
There were no "modern" human species 2,5 My ago


What kind of idiot takes my statement about the lack of divergence across 2.5 million years and informs others that there were no "modern" human species 2.5 million years ago?

Had I not used the example of the fish (500 species in 15,000 years), I might have been misunderstood. Instead, I get a display of ignorance. Let's start over:

If 500 species of fish diverged during 15,000 years, why haven't at least 500 species of humans diverged during the past 2.5 million years?
TheGhostofOtto1923
3 / 5 (2) Apr 05, 2014
Why have so few modern human species diverged in 2.5 million years, when 500 species of these fish diverged (e.g., in the same lake) in 15,000 years?
This is the result of the unique combination of technology and tribalism.
http://rechten.el...RID2.pdf

-A tribe which gained a significant tactical or technological advantage over its adversaries could conquer an entire region, killing the males and incorporating the females. It could also extinct inferior offshoots.

We observe similar behavior in apes. Our recorded history is replete with examples of conquerors sweeping across continents, destroying cultures and spreading their seed. There is no reason to think this behavior wasn't the case throughout prehistory as well.

Conflict is what caused our brains to grow. It is what made us human.
JVK
2 / 5 (4) Apr 05, 2014
Conflict is what caused our brains to grow. It is what made us human.


Thanks for clearly stating your opinion.

Why does it appear to be cooperation that leads from ecological, social and neurogenic niche construction to epigenetically-effected socio-cognitive niche construction in other primates and in humans via the conserved molecular mechanisms of ecological adaptations in species from microbes to man?

Aren't conserved molecular mechanisms integrated into the morphological and behavioral phenotypes of ecological adaptations manifested in species diversity, which theoretically results from randomness and conflict? If so, that suggests evolutionary theorists are simply uninformed or simple-minded. Do you have any opinions about that fact?

http://www.socioa...53/27989
JVK
1 / 5 (4) Apr 05, 2014
http://www.scienc...2207.htm

"While all hummingbirds depend on flower nectar to fuel their high metabolisms and hovering flight, coordinated changes in flower and bill shape have helped to drive the formation of new species of both hummingbirds and plants. Remarkably, as many as 25 hummingbird species are able to coexist in some places."

Perhaps the lack of conflict makes them the bird-brained creatures that they still are. If only they could have fought amongst each other, they could have mutated into humans who were naturally selected to leave more offspring via their success in conflicts.

I apologize to those who cannot grasp the fact that my sarcasm comes from putting up with the pseudoscientific nonsense touted by evolutionary theorists, with ridiculous anonymous names and opinions.
TheGhostofOtto1923
4 / 5 (4) Apr 05, 2014
Why does it appear to be cooperation that leads from ecological, social and neurogenic blahblah
Read the link. Cooperation has traditionally been intratribal. The tribal dynamic - internal altruism in conjunction with external animosity - is what guided human development throughout the pleistocene.

Religions only extend this perception of tribe over larger regions and disparate groups. It has only been since the enlightenment that humanity has become able to see itself as a single tribe. But the transition has a long ways to go, and cannot proceed until religions lose their grip entirely on society.
I apologize to those who cannot grasp the fact that my sarcasm comes from blah
Who you talking to mate? Look around you. Conflict is the norm and always HAS been. You can pretend it is otherwise if you want.

Like I say it is only now that we have the chance to end the cycle of overgrowth and conflict. But IGNORING IT doesn't make it go away. We're not birds you see.
osnova
Apr 05, 2014
This comment has been removed by a moderator.
JVK
1 / 5 (2) Apr 06, 2014
Thanks osnova: "A growing body of evidence shows that evolutionary innovations that provide access to ecological opportunities open new adaptive zones across the mammalian tree (Losos 2010; Dumont et al. 2012). The unhinged jaw of baleen whales combined with the newly discovered sensory organ coordinating lunge feeding in rorqual whales enabled these mammals to become the largest known vertebrates (Pyenson et al. 2012). Within the phyllostomid bats, one of the most diverse dietary radiations within mammals, the evolution of skull morphology allowed certain species to feed on harder foods opening a whole new adaptive zone (Dumont et al. 2012; Santana et al. 2012)." http://mbe.oxford...abstract

When the growing body of experimental evidence from mammals continues to only support ecological adaptations, it makes evolutionary theorists appear to be idiots with no knowledge of biologically based cause and effect.
JVK
1 / 5 (2) Apr 06, 2014
Note: Some theorists now readily admit that they are touting only speculation.

"It is appealing to speculate that genetic variants affecting lipid catabolism in modern Europeans were acquired by modern human ancestors through genetic flow from Neanderthals, and then spread rapidly though the ancestral population by means of positive selection." http://dx.doi.org...omms4584 full text is free

If there were experimental evidence to support the opinion above, it would not be mere speculation. However, pseudoscientific speculation (e.g., speculation without experimental evidence) continues to lose whatever appeal it had as experimental evidence of cause and effect continues to show HOW ecological variation results in ecological adaptations, which are manifested in morphological and behavioral phenotypes.

Nutrient-dependent/pheromone-controlled adaptive evolution: a model
http://www.socioa...53/27989
AJW
5 / 5 (2) Apr 06, 2014
a little fire, a little cooking,
JVK
1 / 5 (2) Apr 06, 2014
AJW: Sorry
a little fire, a little cooking
is not a very intelligent thing to say in the context of conserved molecular mechanisms that link nutrient uptake and metabolism to species diversity in species from microbes to man. Did you miss what I quoted about about whales and bats?

Even if you meant well, the comment is a throwback to evolutionary theory and not based on experimental evidence of biological facts, or what is now known to be responsible for jaw development.
RealScience
5 / 5 (3) Apr 06, 2014
In the mouse-to-human model of ecological adaptation detailed in companion reports by Kamberov et al and by Grossman et al (2013), it became clear that a nutrient-dependent single base pair change led to an amino acid substitution


You have claimed before that this mutation (DNA sequence change) is nutrient-dependent, but have failed to provide any evidence for this. Have you found any experimental evidence to support this yet, or are you just a theorist touting speculation?

My sarcasm comes from putting up with the pseudoscientific nonsense touted by an evolutionary theorist - that's you, JVK, who thinks that because your MODEL forbids mutations being selected for somehow trumps evidence that in nature they ARE sometimes selected for.

Captain Stumpy
4 / 5 (4) Apr 06, 2014
My sarcasm comes from putting up with the pseudoscientific nonsense touted by an evolutionary theorist - that's you, JVK, who thinks that because your MODEL forbids mutations being selected for somehow trumps evidence that in nature they ARE sometimes selected for
@RealScience

which is completely hilarious especially given that he has admitted that his own model CAUSES mutations!

@Otto
just a quick warning ... arguing with a college dropout like jvk is like arguing with cantdrive, rygg or zeph... no matter how much logic or how many articles you throw at them supporting your position (or proving the it with studies etc), he will say "nu-uh" and call you an idiot minion for believing empirical data and being able to understand something other than jr. high basics

you should read up on some of his creationist pheromone crap in other threads (yeah, he is THAT guy ... that sells the pheromone perfumes/colognes)
JVK
1 / 5 (2) Apr 06, 2014
A universal trend of amino acid gain and loss in protein evolution http://dx.doi.org...ure03306 -- may have been the first to eliminate the idea of mutations from evolution in the context of the amino acid substitutions that differentiate the cell types of all individuals of all species.

Nevertheless, despite detailing the involvement of nutrient-dependent amino acid substitutions in the pheromone-controlled physiology of reproduction in my model and in a series of published works during the past two decades, almost every time the topic of evolution comes up -- and despite the experimental evidence that shows how impossible it is for mutations to result in species diversity -- the same anonymous fools make the same comments about me without ever addressing the content of my published works, or of any other published works -- unless the published work contains the word "mutation."

At that point, everything about evolution becomes mutation-driven to idiot minions.
JVK
1 / 5 (2) Apr 06, 2014
The emergence of quorum-quenching lactonases (QQLs) within different superfamilies
exemplifies how nutrient-dependent amino acid substitutions are controlled by species-specific pheromones. The role of pheromones in mediating cell type differentiation constitutes a well established experimental model. http://www.ncbi.n...3249062/

Only the idiot minions of biology teachers who believe in mutation-driven evolution remain unconvinced. They appear to think that the molecular mechanisms of ecological adaptations are not the same in every genera. They want mutations to cause something that somehow benefits organisms, despite the biological facts that show mutations perturb protein folding, which is never beneficial, although it may not always be pathological.

Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors
http://www.socioa...ew/17338
RealScience
5 / 5 (2) Apr 06, 2014
@JVK - I've addressed the papers that you have cited, regardless of whether or not they contain the word 'mutations'.
For example, the paper you just cited says:
we examined human singlenucleotide polymorphisms (SNPs) polarized unambiguously by orthologous chimpanzee sequences. Because a majority of even non-synonymous human SNPs are effectively neutral

SNPs are among the most common mutations (DNA sequence changes), so your citation is saying that most are not even detrimental at all, but merely neutral. And the entire paper is on DNA sequence changes (mutations) that change protein sequences, with these changes ACCUMULATING in species' DNA, and the paper says that this has been going on for billions of years.

@Captain - and even more hilarious is that yet again JVK cites a paper that CONFLICTS with his hypothesis that all mutations interfere with protein folding in a way that makes them so detrimental that they can never be a part of evolution.
JVK
1 / 5 (2) Apr 06, 2014
Why are you ignoring the Nature Communications paper (i.e., speculation)?

"Though Zuckerkandl and Pauling saw the clock as compatible with natural selection, it would later become the basis of the neutral theory of molecular evolution, in which genetic drift rather than selection is the driving force of evolution at the molecular level."
http://en.wikiped...kerkandl

We now know that ecological variation is the driving force of adaptation at the molecular level, which means that mutation-driven evolution is pseudoscientific nonsense and that ideas about genetic drift are nonsense that has not been supported by experimental evidence.

The claim that SNPs are among the most common mutations does not link them to evolution. The claim that nutrient-dependent SNPs are responsible for ecological adaptation links them directly from Darwin's conditions of nutrient-dependent pheromone-controlled life to morphological and behavioral phenotypes in species from microbes to man
JVK
1 / 5 (2) Apr 06, 2014
What kind of idiot minion ignores nearly 50 years of accumulated experimental evidence that was predicted when Dobzhansky wrote in 1964 "The notion has gained some currency that the only worthwhile biology is molecular biology. All else is "bird watching" or "butterfly collecting." Bird watching and butterfly collecting are occupations manifestly unworthy of serious scientists!"

http://icb.oxford...citation

That was a rhetorical question. RealScience and SSgt Stumply exemplify the idiocy of those taught to believe in ridiculous theories. They are incapable of thinking in any other terms no matter how much experimental evidence is offered that clearly shows they were taught pseudoscientific nonsense.

I mention this, as there may still be hope for others who were taught the same thing. Your teachers failed you; educate yourselves or forever be considered your teacher's idiot minions.
JVK
1 / 5 (2) Apr 06, 2014
"Nothing in every day life evokes the nature of life."
http://www.scienc...06004781

Try this experiment. Do not eat for a day. Report how you feel about the nature of life. If you do not feel it is nutrient-dependent, do not eat until you begin to feel death by starvation approaching.

If you still do not feel that the nature of life is nutrient-dependent, please advise the coroner to list 'evolutionary theory' as your cause of death.
JVK
1 / 5 (2) Apr 06, 2014
http://www.scienc...06004781

"All we know is that experiential worlds arise, (no doubt at different galactic times and
places) long after the universe's origin, and appear to be linked to the evolution in
biological entities, of central nervous systems. We also know our biological systems to have
originated, long before any experiential worlds, and that necessarily it had to be so."

What serious scientists know is that physics, chemistry, and molecular biology confirm life is nutrient-dependent and that species diversity is pheromone-controlled via the metabolism of nutrients to signals that control the physiology of reproduction in species from microbes to man.

See, for example, the article and discussion of "A Challenge to the Supremacy of DNA as the Genetic Material" http://blogs.plos...aterial/

Alternatively, be all that you can be: an idiot minion!
RealScience
5 / 5 (2) Apr 06, 2014
"Some theorists now readily admit that they are touting only speculation"
...
Why are you ignoring the Nature Communications paper (i.e., speculation)?

The paper does far more than tout ONLY speculation – it starts with speculation and then presents RESULTS that SUPPORT the speculation. E.g., "We show that genetic variants shared between modern humans and Neanderthals, but distinct from chimpanzees, are specifically enriched in genes involved in lipid catabolism in contemporary humans of European, but not East Asian descent".

The authors then further speculate that these variants gave humans with these Neanderthal genes a selective advantage, but then note that that is not the only consistent explanation.

You are a theorist (you create models) touting your speculation (that mutations cannot be selected for because of biophysical constraints on protein folding). But in contrast to the Nature Com paper, you have not presented ANY results that support your speculation.
JVK
1 / 5 (2) Apr 06, 2014
From Kohl (2013) http://www.socioa...53/27989 After detailing the conserved molecular mechanisms across species, I wrote:

"Two additional recent reports link substitution of the amino acid alanine for the amino acid valine (Grossman et al., 2013) to nutrient-dependent pheromone-controlled adaptive evolution. The alanine substitution for valine does not appear to be under any selection pressure in mice. The cause-and-effect relationship was established in mice by comparing the effects of the alanine, which is under selection pressure in humans, via its substitution for valine in mice (Kamberov et al., 2013).

These two reports (Grossman et al., 2013; Kamberov et al., 2013) tell a new short story of adaptive evolution. The story begins with what was probably a nutrient-dependent variant allele that arose in central China approximately 30,000 years ago.... "

That is not speculation, and it's not pseudoscientific nonsense.
JVK
1 / 5 (2) Apr 06, 2014
The authors then further speculate that these variants gave humans with these Neanderthal genes a selective advantage, but then note that that is not the only consistent explanation.


What kind of idiot does not realize that speculation is not explanation?

That was a rhetorical question. Idiot minions realize nothing. They think speculation is explanation.
RealScience
3 / 5 (2) Apr 06, 2014
The story begins with what was probably a nutrient-dependent variant allele that arose in central China approximately 30,000 years ago.... "

That is not speculation, and it's not pseudoscientific nonsense.


"what was probably a nutrient-dependent variant allele" is speculation.

Neither Grossman nor Kamberov suggests that the allele is a nutrient-dependent variation, so it is YOUR speculation, not theirs.
Do you have any experimental evidence to support your speculation that the variation (rather than selection for the variation after it occurs) is nutrient dependent?

RealScience
5 / 5 (2) Apr 06, 2014
The authors then further speculate that these variants gave humans with these Neanderthal genes a selective advantage, but then note that that is not the only consistent explanation.


What kind of idiot does not realize that speculation is not explanation?


What kind of an idiot would interpret that to mean that SPECULATION is an explanation rather than that 'these variants gave humans with these Neanderthal genes a selective advantage' is an explanation? Especially in the context of that section of the paper:
It is appealing to speculate that genetic variants ... were acquired by modern human ancestors through genetic flow from Neanderthals, and then spread rapidly ... by means of positive selection. ... It is noteworthy, however, that our observations are compatible with both introgression and incomplete lineage sorting hypotheses explaining the excess of genetic variants shared between contemporary humans and Neanderthals in out-of-Africa populations.


anonymous_9001
5 / 5 (4) Apr 06, 2014
"Nothing in every day life evokes the nature of life."
http://www.scienc...06004781

Try this experiment. Do not eat for a day. Report how you feel about the nature of life. If you do not feel it is nutrient-dependent, do not eat until you begin to feel death by starvation approaching.

If you still do not feel that the nature of life is nutrient-dependent, please advise the coroner to list 'evolutionary theory' as your cause of death.


In the same way a car is gasoline-dependent. It's a useless descriptor.

Edit: And you still provide no mechanism for how nutrients cause deterministic allele changes.
Captain Stumpy
3 / 5 (2) Apr 06, 2014
@Captain - and even more hilarious is that yet again JVK cites a paper that CONFLICTS with his hypothesis that all mutations interfere with protein folding in a way that makes them so detrimental that they can never be a part of evolution.
@RealScience
yep! just hilarious!
sometimes I wonder if he is capable of comprehending hat he reads, but then I see that he is , BUT he is very selective. He chooses to believe selectively as well, which makes him more along the lines of a fanatical religionists type rather than scientist... there is no logic or objectivity : he has ALREADY CHOSEN a result, and now he tries hard to prove it with his work, regardless of the reality around him.

and he calls US idiot minions... fascinating really

I have made a killing on his posts!

KEEP UP THE GOOD WORK REALSCIENCE... AND ANON9001
JVK
1 / 5 (2) Apr 06, 2014
As in the past, I will now abandon this discussion. There is no point to discussion with idiot minions.

My published works are easy to find, and all are open access except for my book. The invited submission now in review is titled:

'Nutrient-dependent pherormone-controlled ecological adaptations: from atoms to ecosystems'

James V. Kohl (founder: Pheromones.com)

Captain Stumpy
3.7 / 5 (3) Apr 06, 2014
As in the past, I will now abandon this discussion. There is no point to discussion with idiot minions.

My published works are easy to find, and all are open access except for my book
poor jvk
NICE tantrum...
anyone who ignores the blatantly obvious mutations in http://phys.org/n...lts.html to tout their own failed philosophy
(which is actually included I the modern theory of evolution because it also causes mutations) while calling everyone else an "idiot minion" because we are actually educated and we learned the basics...
well, he HAS to be the biggest IDIOT MINION of them all!
especially when he cant answer questions and when backed into a corner, quits and goes home crying

nice jimmy... at least we know how to get you to shut up and go away now!

Captain Stumpy
3.7 / 5 (3) Apr 06, 2014
As in the past, I will now abandon this discussion. There is no point to discussion with idiot minions.

almost forgot

THANK YOU little jimmy! You've made me a LOT of money so far with your answers and posts!

I made enough money predicting your behavior in my psyche class that I paid for all my books this semester as well as bought a new Laptop (even though it has Windows8 which sucks... it IS a quad core and I am going to put Linux on it)

anonymous_9001
5 / 5 (3) Apr 07, 2014
As in the past, I will now abandon this discussion. There is no point to discussion with idiot minions.

My published works are easy to find, and all are open access except for my book. The invited submission now in review is titled:

'Nutrient-dependent pherormone-controlled ecological adaptations: from atoms to ecosystems'

James V. Kohl (founder: Pheromones.com)



All you have to do is provide a simple answer. Naming the mechanism you think is responsible for said nucleotide substitutions would take you no more than 5 seconds. Unless your publication in review is drastically different than your current ones, you will not name said mechanism in that one either.
anonymous_9001
5 / 5 (3) Apr 07, 2014
Oh, and I'll help you out a bit by ruling out things you've previously said when I've asked this question-

pre-mRNA
glucose dehydrogenase

Both hilariously bad answers. At least glucose dehydrogenase is an enzyme, but, again, as the name implies, all it does is dehydrogenates glucose.
cjn
5 / 5 (2) Apr 07, 2014
Looks like I missed this "discussion". I would still like an answer for why there is so much genomic variation while there is limited numbers of nutrient-stimuli.

Looks like the troll hunt continues!