2. On March 7, 2013, Mendez and colleagues reported a most
amazing discovery: an ancient Y chromosome that is basal
to all other human Y chromosomes in the phylogenetic tree.
The divergence time of the most recent common ancestor
(TMRCA) of all Y chromosomes was estimated to be 338,000
years ago, and possibly even 581,000 years ago
4. “In contrast to the estimates of all previous studies, our
estimate of the Y chromosome TMRCA predates both
that of known mtDNA lineages and of the likely time of
origin of AMHs on the basis of current fossil evidence.”
(Mendez et al. 2013)
“…we should not be surprised that the Y chromosome
genealogy does not match the currently accepted
phylogeny of human populations…” (Mendez et al.
2013)
17. Estimating the age of a population requires us to consider
three variables:
1)Generation time.
2)Mutation rate (number of mutations/generation time).
3)Number of mutations.
Generation Time × Number of Mutations
Age =
Mutation Rate
18. Let us assume that a hypothetical tribe has a generation
time of 1 year and a mutation rate of 0.1 mutations per
generation. If we find 10 mutations in the Y chromosome of
one individual, we can easily calculate that the age is:
1 x 10/0.1 = 100 years old
We can easily make the age look older by using a slower
mutation rate (say, 0.05 instead of 0.1)
1 x 10/0.05 = 200 years old.
… and a longer generation time (say, 2 instead of 1)
2 x 10/0.05 = 400 years old.
… and miscount the number of mutations (say, 20 instead
of 10)
2 x 20/0.05 = 800 years old!
19. In a similar manner, the TMRCA estimate by Mendez et
al. (2013) and Hammer (2013) was reached through
inadequate statistical and analytical methods, each of
which contributed to its inflation, as we shall show in
the following.
We will also show that the model the authors invented
has devastating implications for our species as it creates
a space-time paradox that may mark our (retroactive)
end!
20. "How did Mendez et al. (2013)
misled thee? Let us count the
ways...”
With profuse apologies to Elizabeth Barrett Browning
21. 1. The authors derived the Y-specific substitution rate from
autosomal mutation rates instead of using previously
inferred Y-specific substitution rates.
Why is it wrong?
1) Substitution rate on the Y chromosome is NOT linearly related to the
autosomal rate.
2) The mutation rates were calculated for one generation and are NOT equal
to the substitution rates from our most ancient ancestor to these days.
23. 2. They used a generation time of 40 years.
Why is it wrong?
Generation time in humans was never 40 years!
24. Remember our hypothetical example?
Higher generation time will increase the
age of the Y chromosome.
25. 3. They used sequences of unequal lengths in the comparison
between the newly found lineage A00 and the recognized basal A0.
The authors sequenced 240 kb of the newly found chromosome
(A00) but only reported 75% of it. In their comparison,
mutations were counted on all the 240 kb of the A0 chromosome
but only along portion of the A00 chromosome.
Why is it wrong?
A00
Because that’s cheating (or at least a
deep-tissue massaging of the data)!
A0
??
?
26. Remember our hypothetical example?
Miscounting the number of mutations will
increase the age of the Y chromosome.
27. The conclusions of Mendez et al. (2013)
create a space-time paradox.
To make the new Y chromosome look even older, Mendez et al.
(2013) invented a new branch of statistics:
1. Confidence intervals were used for predictions instead of
prediction intervals.
2. 90% confidence intervals were deemed sufficient instead of the
customary 95% or 99%.
3. The “median” and “standard deviation” of the five numbers (9,
10, 11, 15, and 26) were calculated as 14.2 and 3.12, respectively,
instead of 11 and 6.98 in typical algebra.
4. Normal distribution was deduced on the basis of 5 data points.
28. The conclusions of Mendez et al. (2013)
create a space-time paradox.
Correcting these errors yields a most
remarkable finding!
The number of mutations per generation has
negative values. That is, some events are
predicted to have occurred in the future.
(Grammar is not the only thing being abused
by their work.)
29. Therefore, a possible scenario is that the most ancient
man in the world has not yet been born.
In principle, thus, the mother of the unborn most ancient
male Homo sapiens may decide upon reading the paper
by Mendez et al (2013) not to conceive. Such a decision
may spell the retroactive end of our species.
30. Mendez et al. (2013) may become very rich by selling their
findings to Robert Zemeckis & Bob Gale to serve as the
basis for Back to the Future IV.
From: Back to The Future I (1985)
31. Fortunately, a normal distribution
cannot be deduced from 5 data points,
so humanity may be safe...
32. Using traditional methodology, we
estimated the Y chromosome age to be:
208,300 years (95% CI = 163,900-260,200).
Slightly more ancient than previous
estimates… but still in the range of the
logical.
33. In summary
We have shown that consistently throughout their
examination, Mendez et al. (2013) have used
assumptions, approximations, numerical miscalculations,
and data manipulation that inflated their final estimate.
Our estimate excludes the possibility of
introgression with most ancient hominin species.
34. Our paper:
The “Extremely Ancient” Chromosome that Isn’t: A Forensic Bioinformatics
Investigation of Albert Perry’s X-degenerate Portion of the Y Chromosome
Eran Elhaik1, Tatiana V. Tatarinova2, Anatole A. Klyosov3, and Dan Graur4
Department of Mental Health, Bloomberg School of Public Health, Johns
Hopkins University, Baltimore, MD 21205-2103, USA
2
Department of Pediatrics, Children's Hospital Los Angeles and Keck
School of Medicine, University of Southern California, Los Angeles, CA
90027, USA
3
The Academy of DNA Genealogy, Newton, MA 02459, USA
4
Department of Biology & Biochemistry, University of Houston, Houston,
TX 77204-5001, USA
1
was published in the European Journal of Human Genetics.
35. Relief: Adam has never engaged in
zoophilic relationships with other
species.