Human Uniqueness: What is the evidence from the scientific record?


#1

Did symbolic thought emerge with modern anatomy, or did it occur at a later time?


(Andrew M. Wolfe) #2

Paging @aleo, for an extended discussion of the Great Leap Forward…


(George Brooks) #3

@pmorris

I think most people would say that symbolic thought existed even with hominids prior to Neanderthal.

But symbolic thought is muchly over-rated.

Symbolic thought is not equivalent to the acquisition of Moral Agency (no matter how God or you define Moral Agency).
Though I would easily say, with no lack of confidence, symbolic thought must come before Moral Agency.


#4

Some equate symbolic ability and moral agency with the Amago Dei (Image of God). Is it the Amago Dei that makes homo sapiens, homo sapiens sapiens? If the Biblical Adam was part of an existing homo sapiens sapiens population, what is it about the Amago Dei that distinguishes him from that population, in a biological sense? If the Amago Dei is strickly a spiritual distincrion, what are we to make of the scattered human population at the time, who lived and died during that period? On the other hand, if the Amago Dei evolved over the period of time from the first evidence of AMH (some 300K years ago) to the first signs of symbolism (50K-70K years ago), then that would better fit BioLogos’ model. Otherwise, we are left with pure speculation regarding Adam’s non-Amago Dei community.


(George Brooks) #5

@pmorris

You are mixing apples with oranges.

Homo sapiens sapiens is the scientific nomenclature … which knows nothing of the Amago Dei.

I wouldn’t be surprised if the Amago Dei is what, in God’s eyes, makes humans moral agents… and/or morally responsible.

But the Amago Dei has nothing to do with the scientific classification.


(Peaceful Science) #6

Regarding human uniqueness, we are genetically-modified apes, but we are more than just apes. Scientifically speaking, we are entirely continuous with the animal kingdom, but also discontinuous with it. We are of the dust of the earth, but we bear the image of something greater.

This article and video might help…

http://peacefulscience.org/more-than-apes/


(Christy Hemphill) #7

It’s Imago Dei, people.


#8

So then if representative Adam and Eve possessed the first moral agency, was it only their progeny that inherited it, or were their existing community/population endowed with it as well?


(George Brooks) #9

@pmorris

Great question - - - and this is where @Swamidass has been focusing a lot of his examination.

After 1800 or 2000 years, everyone alive at that time would be a common descendant of Adam & Eve (as well as of other couples from that time frame) - - and thus would have the “genealogy” necessary (but not necessarily the specific chromosomes of Adam & Eve).

Side information and details discussed at length below.

Below is text I wrote for no good reason - - I was answering the wrong question! But I’ll keep it here for future reference.

The short answer is: even with the very weakest assumptions of travelers from one part of the civilized planet to another part (say 1 traveler in 50 years? or something along those lines), within 2000 years, multiple mating pairs become “common ancestors” to everyone now alive on the Earth. So if Adam and Eve begin mixing with the rest of humanity sufficiently early, by the time of the birth of Jesus, there isn’t anyone on the planet that is not a descendant of Adam & Eve.

Note: This is also true of several other mating pairs alive in the population. It’s quite an interesting discovery:

While Common Genealogy is intuitively understandable - - some of us can trace our ancestry back to General Lee of Virginia and others to Mayflower passengers from 1620. But what is not usually grasped is that if you use normal geometric progressions, the entire world would be filled with the Descendants of Charlemagne (circa 800 CE).

But this is not actually true. What happens is that without ready knowledge of which cousin is related to any other cousin, mateable men and women confined by the usual national or regional borders and barriers, almost inevitably meet and mate with a not-too-distant cousin: say, around the 5th to 7th Cousin. This causes Pedigree Collapse, which means a person ends up having far fewer ancestors than a simple expanding chart would account for!

Mainframe scenarios, running the usual possibilities, even with low human mobility, leads to two surprising conclusions:

Main Conclusion: There are multiple mating pairs that were alive about 2000 years ago, that are the common ancestors of everyone alive today.

Corollary: There are many mating pairs that were alive about 2000 years ago with not a single suriviving descendant in the world today.

Genealogy vs. Genetics?
Just as surprising, perhaps, is that while everyone can be certain that 4th cousins have a common set of grandparents (and we can track that with vital records) - - the fact that human genetics comes in 23 pairs and mitochondria, within just a few generations virtually none of your common ancestors genetics survives into the new generation.

46 chromosomes get cut in half at conception (23 from mom, 23 from dad, plus genetic material from the mother’s mitochondria; the especially unique contribution from the father Father’s “Y” chromosome).

The Grand children, on average, get 11 or 12 chromosomes that originally came from one of the 4 Grand parents.

The Great Grand children, on average, get 5 or 6 chromosomes from each of the Great Grand parents.

The Great x2 Grand children, on average, get 2 or 3 chromosomes from each of the Great x2 Grand parents.

The Great x3 Grand children, on average, get 1 or 2.

The Great x4 Grand children, on average, are lucky to get 1 chromosome each from the Great x4 Grand parents.

Now, of course, these are averages, and clusters do occur. But like any Vegas tourist knows … no streak lasts forever.

That’s why it is extremely rare for there to be an uninterrupted line of females (or males) for multiple generations. Just one skip, and the mitochondria (or the Y chromosome) is lost from all future generations!


#10

There are also cross over events during meiosis that swap segments between chromosomes in each pair. From my reading, there are about 2.5 cross-over events per chromosome per individual.

Therefore, a single chromosome can be a mixture of more than one grandparent.


#11

I think the main import of my question was missed. Let me ask again, this way: at the time Adam & Eve received moral agency, they were already living among an existing homo sapiens sapiens population. From the research, that human population was dispersed throughout Central, and East Africa, as well as parts of Europe. Was the dispersal of moral agency linier through Adam’s progeny, or also laterally through social contact with those other humans at the time? If only via Adam’s progeny, Is it possible that progeny of those non-moral agent humans exists today?


(George Brooks) #12

@T_aquaticus.

Agreed. Absolutely. And I do love that illustration!

But since by your own words, 2.5 events per person, we might say that the effect is to turn 23 chromosomes into the theoretical equivalent of “23 carriers x 2.5 = 69 buckets of Genetic Information” - -

So instead of talking about a single chromosome as a single bucket … it can be expanded into 2.5 conceivable buckets.

But eventually, we are going to have more generations than buckets, and the odds of having even a portion of a specific ancestor’s genetic information is going to hover around zero, yes?


(Peaceful Science) #13

It is clear (at least to me) that even advanced animals have some sense of moral agency. They have sense of fairness and justices. This is not what makes human different, it would seem to me.


(Peaceful Science) #14

There are closer to 300 per generation.

Here is the math you are looking for:

http://www.math.ku.dk/~wiuf/journalWiuf/genetics147.pdf

And, because of this, genetic ghosts are a real thing.

https://arxiv.org/abs/1401.3668


#15

If my understanding of population genetics is correct . . .

If there is no selection over many generations, then the odds of any one person having their genome represented in a distant descendant approaches zero (but doesn’t quite get there). It is a bit like the lottery where the odds of any one person winning is very low, but the odds of someone winning is very likely. In this particular case, it is entirely possible for one ancestor to be disproportionately represented in later generations just due to luck. I think this is all tied up in the equations for linkage disequilibrium which I am not that familiar with, but I would imagine that it is similar to the fixation of a mutation which has a 1/(2N) chance of reaching fixation, where N is the population size. Also, this picture can change if there is selection for or against specific alleles.


#16

There appears to be a wide disparity in reported recombination rates which isn’t unheard of for data sets like these.

"By mapping the genotyping results from each sperm cell to the two somatic haplotypes obtained by microfluidic direct deterministic phasing (DDP) of single lymphocytes (Fan et al., 2011), we detected single-chromosome deletions in two cells (Figure 5A), whereas the other 91 cells gave a total of 2,075 autosomal crossover events (22.8 ± 0.4 SE [±3.7 SD] in each sperm) (Figure 2D
and Table S2)."
reference

I’m still wishing I had taken that pop gen class at university. :wink:


(George Brooks) #17

@T_aquaticus

I think I can live with what you describe. Obviously, there is some infinitessimal probability that I do, indeed, have a gene or two from Charlemagne. I am his genealogical descedent… I’ve proved it and everything … me and my millions of cousins.

But it’s low enough that nobody is going to expect to find a gene from Charlemagne in my genome.

So… genealogy can run eternally … but genetic contribution becomes an asymptote of 0.


(George Brooks) #18

Excellent, @Swamidass !

"The Existence and Abundance of Ghost Ancestors in Biparental Populations…"
by Simon Gravel, Mike Steel - (Submitted on 15 Jan 2014 (v1), last revised 2 Mar 2015 (this version, v2))
"We use this result of J. Chang to prove a curious corollary under standard models of recombination:

there exist, with high probability, individuals . . . who are simultaneously [:]
.
.
[GENETIC category] (i) genealogical ancestors of . . . of the individuals at the present, and
.
[GENEALOGICAL category] (ii) genetic ancestors to . . . of the individuals at the present."
.
.
.
“Such ancestral individuals - ancestors of everyone today that left no genetic trace – represent `ghost’ ancestors in a strong sense.”

My spine started to tingle a little bit here … !!!


#19

Those genetic tests also focus on markers that are widespread in a given population, but somewhat specific to that population. Therefore, it can pick up very small contributions from a single shared ancestor.


(George Brooks) #20

@T_aquaticus

Yes, that’s why i had National Geographic test my genome.

Let’s just say, their conclusions were less than specific.

But in general, I think we can rightly agree that Genealogy can be traced for thousands of years,
even when there are no genetic markers to work with!