There Was No First Human

by cofty 266 Replies latest watchtower beliefs

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  cofty

  We have a specific definition of a square. - JWS

  But we don't have one of a human, and we have no need of one in evolutionary terms.

  It is the same in any lineage. Scientists have raging arguments over whether certain fossils are reptile-like mammals or mammal-like reptiles.

  Go back along a line of human ancestors with every woman holding the hand of her mother. Eventually - 6 million years ago - you will meet Pan who is clearly not human by any sensible definition. But as you walk down the line where are you going to draw your line? Whose hand will you take from that of her mother?

  At some point, that variation fit the definition of human, wheras the parents did not. The change would have been tiny, but just enough to cross that line

  No. A million times NO.

  It is the "Dead Hand of Plato" that causes this confusion. There is no essential "human" or "rabbit" by which all specimens can be compared.

  We give things labels but they are all fuzzy.

  All of life is change.
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  cofty

  I am now reading ' Mitochondria and the Meaning of Life '. Once I have completed that I will comment on the matter of genes - Earnest

  It's a great book but not one that will give you too much on genetics. I thoroughly enjoyed it though.

  His other book "Life Ascending" is superb.

  I am also reading his other book on Oxygen - its quite hard work.
• 

  Apognophos

  I think JWS' question is very understandable when you consider that we have a little something called Latin nomenclature (or whatever the preferred term is these days for the Linnaean system), whereby we label one kind of life "Homo sapiens sapiens" and another kind "Homo neandertalensis". The implication is that there is a definition of what a human or a Neanderthal is, just like a Platonic ideal. So maybe he's asking, "How can we keep applying a certain species name to a kind of life if it is changing over time?" For instance, what if one day 10,000 years from now, we can move things with our giant, pulsating brains, as in some old-timey science fiction? Will we still call ourselves H. sapiens? What if there are some people who can do this and some who cannot?

  Perhaps the most direct general answer to the question is, "A life form is no longer the same as it used to be when it cannot reproduce with the older kind of life form or a sister kind of life that descended from the same ancestor."
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  cofty

  "If there is a 'standard rabbit' the accolade denotes no more than the centre of a bell-shaped distribution of real, scurrying, leaping variable bunnies. And the distribution shifts with time. As generations go by there may gradually come a point, not clearly defined, when the norm of what we call rabbits will have departed so far as to deserve a different name. There is no permanent rabbitness, no essence of rabbit hanging in the sky, just populations of furry, long-eared, coprophagous, whisker-twitching individuals, showing a statistical distribution of variation in size, colour and proclivities"

  The Greatest Show on Earth by Richard Dawkins

  Chapter 2 "Dogs Cows and Cabbages" sub-heading "The Dead Hand of Plato".
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  atrapado

  Since the sample is finite and not infinite you should be able to pin-point when a small changed cause from non-human to human. Just like jws suggest.

  We might not all agree on what is human but for example lets try this. You start with a humans DNA and you add enough parameters to vary that DNA to include every single human being living today and why not for the last 10,000 years. Then you take your timeline and look for the oldest ancestor that matches that criteria why wouldn't that be the first human?
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  Viviane

  So basically you're suggesting building a criteria set such that the DNA of every modern human would fit through the DNA sifter and look backwards to find the first DNA that would ALSO fit through the sifter?

  First, we don't have DNA from a population in the past to do that, secondly, that's an arbitrary line in the sand, that individual would still be the same species as it's most recent ancestors and descendants.
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  cofty

  So atrapado, what precisely do you think makes us human?
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  atrapado

  Well theoretically is possible. But I rather say we cannot do it than claim there was no first human.

  Here is another theoretical test take a current human and see the oldest ancestor he/she can reproduce with and that will be the first human :)
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  cofty

  What do you think makes us human atrapado?
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  Viviane

  Well theoretically is possible. But I rather say we cannot do it than claim there was no first human.

  My bigger point is that when you decide that, at some point, a population was human, you are still making an arbitrary distinction. Populations evolve into different species, not individual members of that population.