I'm brazilian and today I've came across this news published in a religious brazilian site. It's about a recent study that says that 9 to 10 species on Earth today, including humans, came into being 100,000 to 200,000 year ago.

Also, according to the site, that study supports what the bible says about the origins of life.

I'm pretty sure it's creationist rubbish, but I couldn't understand the conclusion of that study. So, I wish someone would explain to me that conclusion in lay terms. And, taking the opportunity, I'd also like to know if the paper is peer-reviewed and realiable.

Thanks in advance.

Source: https://phys.org/news/2018-05-gene-survey-reveals-facets-evolution.html

  • What is exactly the claim that you want to have it confirmed or not? Can you please clearly write out a clearly defined claim for which we could work on to write an answer. For the moment, I am afraid the question is unclear. – Remi.b Jul 24 at 0:50
  • I didn't ask for a confirmation of a claim but for the conclusion of the study (if there's one). I think my questions are pretty clear. – Ricardo R. M. Jul 24 at 1:25
  • Do you want us to copy-paste their conclusion? Have you read their conclusion (see their section Summary and conclusion). Was there anything specific that was unclear to you from this section? – Remi.b Jul 24 at 1:28
  • To answer your side question... Yes, the paper Stocker and Thaler (2018) has been peer-reviewed. It is published in the Journal of Human Evolution, which a journal of average to low impact. – Remi.b Jul 24 at 1:37
  • The conclusion is too technical for my level of english. I'm not a scientist, but I like science, so I decided to try this board expecting that someone could explain that conclusion in plain terms. And to say whether the paper is reliable. – Ricardo R. M. Jul 24 at 1:39
up vote 2 down vote accepted

They key qualifier is living species, many living species have relatively recent origins, that is exactly what you would expect in an ever changing ever evolving biosphere. That is like stating that most cars on the road are less than ten years old, OK, but that's not really a surprising statement. If you plotted a bell curve of how old all current animal species are the bulk would be fairly recent geologically speaking. Species have a lifespan. The average lifespan of a mammal species is around a million years so simple statistics will mean most living mammal species will be less than half that. No one is surprised when you say most of the data points in a randomly distributed set fall within one-two standard deviations.

In fact based on back of the envelope calculations, if the average lifespan of a species is ~ 1 million years, and we assume they are randomly distributed, (they are not, extinction events exist which would shorten it), then just based on the 68–95–99.7 rule, 95% of living (at or below the mean) species should be less than 320,000 years old.

Now the paper itself is meaningless, it's justification is largely circular: define species based on mitochondrial mutation rate, (which of course is a time based calculation), then use that definition to say most species fall within a certain time period. You can change the number of mutations in your definition of species to fit your conclusion. Even a species has existed a single unfractured population for millions of years will count as a recent species by that definition. It is circular reasoning, made worse by using mitochondria, which are not undergoing recombination so variance is basically only controlled by generation time. If a population splits into two or remains a single population its mitochondrial variance will remain largely unchanged. Interestingly they exclude the groups (plants, fungi, ect) in which mitochondria undergo recombination.

Really the only conclusion you can draw from the article is most journalists don't understand statistics or genetics.

  • I like the cars on the road analogy. If you used the same logic as the paper you'd be concluding that the automobile was invented sometime after 2000. – Bryan Krause Jul 24 at 17:04

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