Researcher disputes claim that humans can distinguish one trillion odors

ASU researcher disputes claim that humans can distinguish 1 trillion odors
Arizona State University researcher Rick Gerkin disagrees with findings made public last year in the journal Science that humans can smell at least 1 trillion odors. In a new paper published in eLife, Gerkin and co-author Jason Castro present several arguments as to why the number of smells humans can distinguish is still unknown. Credit: Andy DeLisle

An Arizona State University researcher is calling into question recent findings that the human nose is capable of distinguishing at least 1 trillion odors. Rick Gerkin, an assistant research professor with ASU School of Life Sciences, says the data used in a study made public last year does not support this claim.

According to Gerkin, this is important because findings from the 2014 study published in the journal Science are already making their way into neuroscience textbooks, misinforming up-and-coming investigators and cutting off potentially productive lines of research that do not adhere to those findings. Researchers from The Rockefeller University and Howard Hughes Medical Institute authored that paper.

The new paper challenging the findings appears today in the journal eLife.

"We disagree with several aspects of the 2014 study," said Gerkin, who co-authored the paper with Jason Castro, a professor with Bates College in Maine. "First, the assertion that humans can discriminate between at least 1 trillion odors is based on a fragile mathematical framework—one that's capable of creating nearly any result with small variations in the data or the experiment design. So the result in question could be tens of orders of magnitude—a factor of one with dozens of zeros after it—larger or smaller than first reported."

"We also point out that the conclusion in the 2014 paper relies heavily on untested assumptions about smell perception," added Castro. "And the equation used actually shows that the number of distinguishable smells is fewer than 1 trillion, not more, making the original claim inaccurate, and in fact the exact opposite of what the calculation actually shows."

Gerkin and Castro show in their paper that if the experiment had used approximately 100 additional subjects, the same analysis would have shown that the could discriminate all possible odors—clearly at odds with the data in the 2014 paper. Moreover, had the researchers used a slightly more conservative statistical analysis, it would have shown that humans can distinguish only 5,000 odors—about the same number generally believed to be true prior to 2014.

ASU researcher disputes claim that humans can distinguish 1 trillion odors
Gerkin and Castro showed that the number of smells estimated in a 2014 paper published in Science was heavily dependent on the number of participants in the experiment, and on the strictness of a statistical test that paper employed. In a new paper published in eLife, the pair show that by choosing alternative values for those parameters -- ones that could reasonably have been used in a parallel experiment -- it becomes possible to estimate any number of smells from the data, including the most or fewest possible from that paper's framework. Thus, the value the original paper did obtain (*) is just one of the many possible defensible estimates. Credit: Rick Gerkin and Jason Castro

According to Gerkin, the number of smells humans can discriminate is the kind of fact that could flow naturally from a deeper understanding of olfaction—something we currently lack, but that must be established to better understand olfactory health and diseases of smell.

"Scientists can easily compute the number of discriminable colors because they know the organization of color perception," said Gerkin. "For example, think about the color wheel we learned in elementary school or the red-green-blue color values that make it possible to display color on television. For smells, there is no accepted 'smell wheel' just yet. To make one, we must first discover the organization of olfactory perception. Only then can a principled calculation be used to determine how many unique smells there really are."

And, the pair added that only when olfaction is better understood can researchers develop the tools needed to address health issues related to smell disorders, which often have a profound, negative impact on human well-being.

Gerkin studies how olfactory perception, learning, and behavior are encoded in the brain. He also pursues neuroinformatics—the development of tools and standards to facilitate the collection, curation, dissemination, and analysis of neuroscience models and data.


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Humans can distinguish at least one trillion different odors, study shows

More information: eLife: dx.doi.org/10.7554/eLife.08127

Science: www.sciencemag.org/content/343/6177/1370.long

Provided by Arizona State University
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Jul 07, 2015
The eLife link at the bottom is broken. The correct URL is http//dx.doi.org/10.7554/eLife.08127

Jul 08, 2015
The scientists attitude toward truth is worth of respect. More scientists like them should join the group to find about the truth. Besides, this disputes showed that the number of participants in a research or study should be large enough or wrong conclusion may be drew. BOC Sciences had pay special attention to that in the various researches.

JVK
Jul 08, 2015
The truth is that RNA-mediated events link the experience-driven nutrient-dependent de novo creation of olfactory receptor genes to the individual and species-specific perception of food odors and pheromones. Olfaction links the nutrient-dependent pheromone-controlled physiology of reproduction to cell type differentiation via the biophysically constrained chemistry of protein folding via amino acid substitutions.

See: http://elifescien...1/e00326
"Importantly, this model provides an elegant balance between plasticity and adaptation; although the potential to detect a wide range of odours, afforded by the exceptional number of genes for receptors, remains intact, the sensory organ becomes 'tuned' and sensitized to odorants relevant to its habitat."

Changes in the microRNA/messenger RNA balance link viral microRNAs and nutrient-dependent microRNAs to the fine-tuning of all cell types in all individuals of all species.

JVK
Jul 08, 2015
The Center for Evolution & Medicine at Arizona State University presents a potential conflict of interest for an assistant research professor with ASU School of Life Sciences.

The Center probably wants to present findings in the context of mutations and the evolution of biodiversity. That is not possible with findings on olfaction.

Feedback loops link odor and pheromone signaling with reproduction http://www.cell.c...l%3Dtrue

Evolutionary theorists probably would like others to believe that random mutations can somehow be linked to the differentiation of cell types in all genera.

Population geneticists have typically tweaked the numbers to make the invention of neo-Darwinism appear to fit the facts about cell type differentiation.

JVK
Jul 08, 2015
Re: Population geneticists have typically tweaked the numbers to make the invention of neo-Darwinism appear to fit the facts about cell type differentiation.
---------------
Exception: They still have not determined how differences in human sexual orientation arise in the context of epigenetically effected RNA-mediated amino acid substitutions that link the nutrient-dependent pheromone-controlled cell type differentiation of all cell types in all individuals of species from microbes to man via their biophysically constrained chemistry of protein folding.

They look at brain imaging, and ask why the behavior of pedophiles is atypical.

See for example: Epigenetically-effected sexual orientation http://perfumingt...ntation/

They remain biologically uninformed social scientists.

Jul 08, 2015
http://perfumingthemind.com/epigenetically-effected-sexual-orientation/
PHISHING and PSEUDOSCIENCE LINK

mixing creationist dogma with actual science means that you promote creationists and their ideals, which is NOT SCIENCE, and proven to be not science here: https://en.wikipe...Arkansas

your prejudice towards homosexuals is already known as it got you canned from a SERIOUS scientists site already
Mere stupidity I will tolerate, but I really don't need to give a platform to homophobes. Kohl has been banned.
http://freethough...s-place/

take your PSEUDOSCIENCE and religious based prejudice elsewhere

JVK
Jul 08, 2015
your prejudice towards homosexuals is already known


See my award winning journal article/book chapter on the development of sexual orientation
The Mind's Eyes: Human pheromones, neuroscience, and male sexual preferences
http://www.sexarc...kohl.htm

Download the powerpoint slides from my Plenary session at the Society for the Scientific Study of Sexuality http://perfumingt...site.ppt

PZ Myers banned me with the claim that I was a homophobe, after I exemplified his errors by reporting this link on chromosomal rearrangements and cell type differentiation in the context of morphological and behavioral phenotypes.

Estrogen receptor α polymorphism in a species with alternative behavioral phenotypes
http://www.pnas.o...abstract

Biologically uniformed science idiots want these differences to be due to mutations and evolution, but they are obviously RNA-mediated.

JVK
Jul 08, 2015
your prejudice towards homosexuals is already known


From my review: Perhaps the creation of diversified human life gave us the ability to recognize differences between our sexual behavior and the sexual behavior of others. Since all life does not beget diversified life, those who judge sexual preferences that do not seem to result in diversified life may be judging creation itself.

It is easy to understand how someone could judge a particular sexual preference, without thought. Unconscious affects that are manifest in the development of human sexual preferences are, by their nature, a part of diversified life that few people think about. What we think about human sexual preferences becomes less meaningful when we realize that most of sexual behavior is not what we cognitively think it should be. Indeed, the largest contributor to sexual preferences that are manifest in the sexual behavior of any species appears to be unconscious affect.

JVK
Jul 08, 2015
Re: RNA-directed regulation of epigenetic processes

See:
1) rna directed https://www.googl...directed

2) rna directed dna methylation https://www.googl...directed+dna+methylation

3) dna methylation and histone acetylation https://www.googl...tylation

4) rna mediated https://www.googl...mediated

Find out who is still touting the pseudoscientific nonsense invented by population geneticists and compare who's who among serious scientists. If you find one evolutionary theorist who knows how cell type differentiation occurs in the absence of RNA-mediated biologically-based cause and effect, please alert others to the representations made by the biologically uninformed science idiot, for comparison.

JVK
Jul 08, 2015
Nutrient-dependent RNA-mediated cell type differentiation, which is controlled by the metabolism of nutrients to species-specific pheromones in species from microbes to man via their physiology of reproduction, links nutritional epigenetics to pharmacogenomics via metabolic networks and genetic networks.

Not one serious scientist does not know that "Feedback loops link odor and pheromone signaling with reproduction" http://www.ncbi.n...16290036

Only theorists claim that the mutations that perturb the feedback loops somehow also can be linked to the evolution of increasing organismal complexity.

Only a biologically uninformed science idiot would link to the page of an atheist blogger like PZ Myers -- http://freethough...s-place/ -- at the same time he tells me to
take your PSEUDOSCIENCE and religious based prejudice elsewhere



JVK
Jul 08, 2015
See also: https://www.googl...n+driven

One of my comments on mutation-driven evolution is here: https://www.googl...IXTNNo7A

http://www.nature...42a.html
Overall, our study provides novel insights into how a single amino acid affects gene regulation in E. coli O157:H7 and that this can have stark implications for the niche specificity of this pathotype.

Another comment is here: https://www.googl...qqo9FtGw

Jul 08, 2015
PZ Myers banned me with the claim that I was a homophobe, after I exemplified his errors by reporting this link on chromosomal rearrangements and cell type differentiation in the context of morphological and behavioral phenotypes
@jk
only a chronic LIAR would blatantly lie in the face of evidence that shows he is not representing a situation as it actually happened... and it took you 5 separate posts to boot!
why?
is it too hard for you to be clear and concise?
or is that part of your need to obfuscate the truth?
http://freethough...s-place/

post # 317
Mere stupidity I will tolerate, but I really don't need to give a platform to homophobes. Kohl has been banned
this means exactly what it said: you are a prejudiced liar trying to utilize other forums as a means to promote your religious hatred and bigotry
http://perfumingt...site.ppt
PSEUDOSCIENCE PHISHING SITE
reported

Jul 08, 2015
Only a biologically uninformed science idiot would link to the page of an atheist blogger like PZ Myers -- http://freethough...s-place/ -- at the same time he tells me to

take your PSEUDOSCIENCE and religious based prejudice elsewhere
So, you are trying to say that an accomplished and ACTUAL scientists is not real unless he is a religious one?
really?

so, by his refusal to allow you to vent your bigotry on HIS web site, you are somehow against him, much like you are now denigrating Lenski, Extavour & Whittaker and many others because they had the gall to not allow you to promote pseudoscience?

to ANYONE with a lot of patience, all they have to do is re-read your own comments on MYERS blog, linked above in my last post: your hatred and delusional religious prejudice is blatantly obvious and your serious bigotry is STILL THERE as a demonstration of your stupidity

read it and weep

JVK
Jul 08, 2015
I suggest that those who do not like being a biologically uninformed science idiot read my published works. They can compare them to my blog posts and to the blog posts of biologically uninformed science idiots like PZ Myers.

The works of serious scientists who understand how the biophysically constrained chemistry of nutrient-dependent RNA-mediated protein folding led to the changes in E. coli reported in Lenski's works, can be compared to facts.

See: The host metabolite D-serine contributes to bacterial niche specificity through gene selection
http://dx.doi.org...2014.242

See also: The Escherichia coli argW-dsdCXA Genetic Island Is Highly Variable, and E. coli K1 Strains Commonly Possess Two Copies of dsdCXA http://www.ncbi.n...1698345/

"We are currently testing the patterns of the nutritional capabilities of different E. coli pathotypes and how these differences affect the expression of their pathogenic factors."

Jul 09, 2015
I suggest that those who do not like being a biologically uninformed science idiot read my published works. They can compare them to my blog posts and to the blog posts of biologically uninformed science idiots like PZ Myers
@jk
1- if you had ANY scientific credibility, you would not be publishing creationist diatribe with scientific papers, which means you are LYING, again
2- MYERS is a published reputable scientist, far above what you've done
3- and most importantly: calling someone a "biologically uninformed science idiot" because they don't read your PSEUDOSCIENCE is like saying we're all going to hell for not reading your stupidity and religion. those of us who do not believe in that BS simply ignore the stupidity and transferrence you are trying to post

face it, Lenski (Especially the first 100K generations up to 2003) experimentally prove that your idiocy re: mutations is not only pseudoscience, but that you don't comprehend biology

JVK
Jul 09, 2015
calling someone a "biologically uninformed science idiot" because they don't read your PSEUDOSCIENCE


I use the definition of idiot that attests to the fact they refuse to learn, not that they are mentally deficient. A science idiot is someone who refuses to link experimental evidence to what he or she has been taught to believe.

A biologically uninformed science idiot is someone like SSgt (ret) James Stumpy who thinks that Lenski's experiments link mutations and evolution. He ignores everything known about the biophysically constrained chemistry of nutrient-dependent RNA-mediated protein folding that links metabolic networks to genetic networks in all genera, and claims that PZ Myers knows best.

http://dx.doi.org...5-4879-3
Excerpt: "How human PGCs maintain relatively stable global RNA expression patterns when DNA methylation is globally decreased by more than 10-fold warrants further analysis."

But not by PZ Myers.

Jul 09, 2015
(Correcting my horrible English)

Despite whatever the number is, the nose is truly a miracle organ. Right along with the eye that can behold colors, and the ear that can perceive 3D sounds in 2D architecture!



And all due to evolution.

JVK
Jul 09, 2015
Relatively stable global RNA expression patterns when DNA methylation is globally decreased arise via the fixation of RNA-mediated amino acid substitutions in organized genomes.

That fact links the epigenetic effects of nutrients to the physiology of reproduction, which links ecological variation to ecological adaptation via metabolic networks and genetic networks in all living genera.

That does not mean that humans cannot knowingly perturb protein folding. It attests to the fact that they have done so during the past ~5000 years.

http://www.nature...-1.11912
Excerpt: Of 1.15 million single-nucleotide variants found among more than 15,000 protein-encoding genes, 73% in arose the past 5,000 years...

If you think we are evolving, review what has been learned from Lenski's experiments. The E. coli are still E.coli, and Captain Stumpy is a biologically uninformed science idiot.

JVK
Jul 09, 2015
Right along with the eye that can behold colors...


Our color perception arose in the context of nutrient-dependent pheromone-controlled fixation of the amino acid substitutions that stabilized our organized genome. The link to trichromatic vision is one of the clearest links from ecological variation to ecological adaptations in primates that has ever been detailed in the context of our biophysically constrained chemistry of RNA-mediated protein folding.

See: Celebrating independence from ridiculous theories
http://rna-mediat...heories/

Jul 09, 2015
An interview with Markus Meister.

http://medicalxpr...nwletter

Jul 09, 2015
Genetic bottleneck
"The researchers found that the European Americans had a larger proportion of potentially harmful variants — probably an artefact of their original migration out of Africa. The first small group of humans that left Africa for Europe experienced a sudden drop in genetic diversity — a 'bottleneck' — owing to the smaller pool of possible mating partners. In the rapid expansion in population size that followed, selection was slow to catch up to and weed out potentially harmful mutations."
http://www.nature...-1.11912

@JVK

Why didn't you include that paragraph?

JVK
Jul 10, 2015
Thanks for asking. It's part of a ridiculous theory that was invented by population geneticists.

Widespread rescue of Y-linked genes by gene movement to autosomes
http://genomebiol...16/1/121

Excerpt: "...an alternative way to compensate for gene loss is to move genes from the degraded Y chromosome to other, non-sex chromosome locations..."

The inventors of neo-Darwinism are wrong. There are no "lower races" and sex differences in cell types didn't evolve.

Cell type differentiation is nutrient-dependent and controlled by the physiology of reproduction in all living genera. Experimental evidence links chromosomal rearrangements to biodiversity instead of mutations. Biologically uninformed science idiots like PZ Myers don't like that fact.

See: One crank dies, another rises to take his place
http://freethough...fSS0jRxE

Jul 12, 2015
@JVK "The Center for Evolution & Medicine at Arizona State University presents a potential conflict of interest for an assistant research professor with .SU School of Life Sciences. 

The Center probably wants to present findings in the context of mutations and the evolution of biodiversity. That is not possible with findings on olfaction. 

Feedback loops link odor and pheromone signaling with reproduction http://www.cell.c...l%3Dtrue

Evolutionary theorists probably would like others to believe that random mutations can somehow be linked to the differentiation of cell types in all genera.

Population geneticists have typically tweaked the numbers to make the invention of neo-Darwinism appear to fit the facts about cell type differentiation.

Two "probablies". What a rigorously reasoned comment.

Jul 13, 2015
@Accounts



Two "probablies". What a rigorously reasoned comment.


It's not surprising coming from a young earth creationist like JVK.

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