October 14, 2011

Echoes from the Past (Oct 14) - the genetic isolation of humankind

I'm planning an entry on Paleolithic and Neolithic navigation but meanwhile, here it goes some stuff (mariner or not) that I find interesting.


Homo genus became genetically isolate thanks to natural spermicide


H. erectus (female) reconstruction
A critical change in a immune system molecule, from Neu5Gc to Neu5Ac, made our ancestors effectively isolated from our cousins from the Pan genus and probably also from the then common australopithecines. 

This change would simply kill any non-human sperm in the uterus or, would it manage to succeed, the resultant fetus. This incompatibility with other hominins may have been critical in the process of speciation of the first Homo species such as Homo erectus, Homo habilis or maybe A. sediba. 

··> Science Daily, Darius Ghaderi et al. at PNAS (PPV for six months or freely accessible in some world regions).


Human thumb (Neanderthal or H. heidelbergensis) found in Sardinia

The finding of a thumb bone in Sardinia, dated to 250-300,000 years ago, may help break the fantasy of ancient humans not being able to navigate. This finding adds to those of Crete (c. 190 Ka ago and the famous Flores hominin), all of which must have crossed vast spans of sea in order to get to their destinations, implying at least some level of navigation. 


In the discussion at NeanderFollia, David indicated further evidence of archaic navigation I was unaware of: H. erectus must have reached Flores c. 900,000 years ago, in what is probably the most ancient navigation feat we can confirm ··> John Hawks, Environmental Grafitti, Adam Brumm et al. at Nature (PPV).

Also there is at least some uncertainty of H. ergaster or some other human species maybe crossing to Europe via the Strait of Gibraltar at similar dates as in Flores or maybe even earlier, but, because of the various possible routes involved this is less conclusive. Instead, Flores, Sardinia and Crete have not been connected to the mainland at any time in the biological history of the genus Homo.


Art workshop found in South Africa

A number of shells with indications of having held ochre have been found in the important site of Blombos Cave, South Africa. The shells had holes which suggest that they were used as containers. Other tools, such as hammers and knives, to work the clay, have also been found.




Babies know justice instictively

While actual perception and interest on fairness varies, a good deal of human babies (15 months old) clearly show interest in fair sharing and will actively share. Other babies have less interest in fairness however but they will share anyhow, even if in a less generous manner. 



Malaria research casts doubt on mitochondrial DNA 'molecular clock'

It seems that the molecular clock is not on streak. Recently it was radically challenged for Y-DNA and it seems obvious that it will not survive in general, at least without radical revisions. A crucial assumption for the molecular clock hypothesis is that the clock ticks regularly or almost so. 

Well, it does not seem to be the case of mtDNA either: certainly not for the primate parasite Plasmodium sp

The use of fossils from the host as absolute calibration and the assumption of a strict clock likely underestimate time when performing molecular dating analyses on malarial parasites. Indeed, by exploring different calibration points, we found that the time for the radiation of primate parasites may have taken place in the Eocene, a time consistent with the radiation of African anthropoids. The radiation of the four human parasite lineages was part of such events. 



Celtic astronomical kurgan found in Germany

Dated to the 7th century BCE, the plan of a burial mound (or kurgan) of the Hallstatt period in the early Celtic area of Southern Germany has been reported. Allegedly the disposition of the wooden posts around the mound inform about the astronomy of the Moon, primarily, and the Sun and they may even describe constellations.



Altamira at risk on short-sighted tourism greed

Millán Mozota denounces at his blog, echoing other researchers, the short-sighted attitude of the Cantabrian authorities who have decided to open the Altamira cave to the public again in spite of the dramatic risk for the art in it.
In the last decade, considerable attention has been paid to the deterioration of the caves that house the world's most prominent Paleolithic rock art. This is exemplified by the caves of Lascaux (Dordogne, France) (1) and Altamira (Cantabria, Spain), both declared World Heritage Sites. The Altamira Cave has been closed to visitors since 2002. Since 2010, reopening the Altamira Cave has been under consideration. We argue that research indicates the need to preserve the cave by keeping it closed in the near future.

The public can enjoy a replica of part of the cave at the nearby museum.



Iberian Neolithic idols

While in Spanish language, I can't but call your attention to this fifth article of Neolítico de la Península Ibérica on the diverse array of idols known from the Neolithic and Chalcolithic of Iberia. Even if you can't read any Spanish, you will no doubt gather some information and visual recreation from simply watching the many images and maps included in this blogpost. For example:

Orange ovals: "eyed" idols (oculados), brown ovals: "plate" idols (ídolos placa)

··> Neolítico de la Península Ibérica[es].


Last minute news:  some iris pattern genetics unveiled ··> The Spitoon.

23 comments:

  1. At the risk of completely wasting my time:

    "A critical change in a immune system molecule, from Neu5Gc to Neu5Ac, made our ancestors effectively isolated from our cousins from the Pan genus and probably also from the then common australopithecines".

    The change cannot have been 'instant'. In other words the individual in which the mutation occurred must have been able to breed with someone or the mutation wouldn't have survived. For some wierd reason you are still looking for some defining moment when we ceased being apes. We haven't ceased being apes.

    "The finding of a thumb bone in Sardinia, dated to 250-300,000 years ago, may help break the fantasy of ancient humans not being able to navigate".

    How so?

    "I was unaware of: H. erectus must have reached Flores c. 900,000 years ago, in what is probably the most ancient navigation feat we can confirm"

    Haven't we know for years that humans had reached Flores at least half a million years ago? And how does it 'confirm' any sort of navigation? Other possibilities spring immediately to mind. But, of course. Your mind is already made up.

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  2. John Hawks, as usual, makes some useful comments:

    "A date of 880,000 years ago for human occupation made for a convenient explanation of faunal turnover on the island, which happened around that time".

    So these other species accompanied the people on their boats?

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  3. Elephants can swim like 50 km and back, and they tow those that are tired. Humans can't... but they can navigate those spans with simple means.

    Faunal change may explain why people went after them, it may also talk of geological changes that made the island more accessible for a time... or whatever. But unlike elephants, people can't swim 50 km and back.

    Tsunami-surfing is not a probable explanation for human migrations across the sea. Otherwise we could even consider that the colonization of Australia happened that way. Why not?

    "For some wierd reason you are still looking for some defining moment when we ceased being apes. We haven't ceased being apes".

    I am not looking for that. I am a proud bonobo (sort of). But still bonobo chicks look a bit too hairy to me (among other strange traits). Bonobo guys on the other hand... are still much like we are - too much.

    But instead you are looking to deny bonobos and our H. erectus cousins, even our own species, their true creative intelligent power, which we know they/we have. After all we have sent people out to the space, we have crossed oceans... why would not be able to build a simple raft?

    Because Terry has decided so? That's no reason.

    "The change cannot have been 'instant'".

    I can't be sure but this is an immunity issue and seems that a quite radical one. Probably the mutant was a man (who that way excluded all other men, and all other male apes, australopithecines, etc.) from effectively reproducing with his daughters, granddaughters, etc.

    Sounds excitingly/disturbingly incestuous but most likely the mutation spread through males, making first their sisters relatively sterile... but only at first. It may have triggered a major bottleneck because if you (fem.) can only have children with your cousin (male)... maybe you do after all.

    "How so?"

    Hope is never lost that some stubborn minds yield to a pile of evidence. It is further evidence of pre-Sapiens navigation, three islands in three different parts of the world, different times, different species (besides the Gibraltar Acheulean issue, harder to prove and all the rivers these relatives had to cross).

    "Haven't we know for years that humans had reached Flores at least half a million years ago?"

    In truth I did not know (or had forgotten). I never paid too much attention to H. floresiensis - my focus is H. sapiens.

    "And how does it 'confirm' any sort of navigation?"

    Flores is three straits away from the Sundaland mainland (in Ice Age periods). Nothing can arrive there but crossing the sea. The Wallace line is not 100% absolute but it's very radical anyhow.

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  4. From my point of view, it seems to me a fantasy to believe that homo erectus have reached to flores island swept away by a tsunami.

    Some scientists are able to develop an bizarre theories; it seems an obsesion to demonstrate that other members of our family homo are inferior to us.

    sad.

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  5. Well, people crossed open water in some fashion. But it need not have been as sophisticated as a Polynesian Waka.

    Of note, the unaided human open ocean swimming record was set by Diana Nyad, Bimini to Florida, no wetsuit, no flippers, no shark cage, is 102 miles (164 km). Don't underestimate what fit humans can do in warm water.

    My guess is that groups of humans could go a long way across warm water just by some of them resting on a log while others hung onto the log and kicked. Easily believable that Homo erectus could do that. Maybe less than 2 km/hr progress, but not hard to do at all in a calm, warm sea.

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  6. Unlike elephants humans have not been observed swimming long distances normally in groups. The record of Nyad (what an appropriate surname: sounds like naiad) is not what most fit people do, much less with the family.

    Instead humans have been observed using all kind of aids, notably rafts and boats. And these are (normally) safe enough to bring your kids and even granny with you.

    The best documented simplest kind of boating device for H. sapiens in the Asian and Australian tropics is three logs tied (sometimes with the central one longer for better hydrodynamics) or its variant of several bamboos tied. That might well have been the "normal raft" of our ancestors: easy to make and multipurposely useful.

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  7. We don't have any way to know what archaic Homo did with perishable materials, but tying 3 logs together with vines (or tying reeds as they do in Peru) should have been well within the ken of the earliest Homo, just the sort of thing I had in mind.

    Sails? No. Neither Native Americans nor Sub Saharan Africans developed sailing. Even if one is clear on the concept, making the fine reed mat sails or textile sails is a lot of work. It is a far from obvious development even for our species.

    Paddles? Maybe. Early Homo likely used hand axes to chop firewood, but we don't have any idea what their fine woodworking skills were. Making a good paddle is a big job. Stone aged modern Homo made them, but it is was labour intensive task requiring hafted stone adzes. Did any early Homo have such a toolkit?

    Were I stranded on an island with only archaic stone tools, and could see my goal on the horizon, I would just use my crude raft as a kickboard/paddleboard and rest on it when I got tired, as groups of surfers do today. The alternative of trying to make a decent paddle, when I am a poor woodworker, is too dismal to contemplate.

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  8. I do not think either that sails are likely before (roughly) Neolithic. Even Neolithic ships appear to have worked better by rowing (but of course it's an open matter).

    You make a big issue of paddles. Agreed that a perfected paddle may require some work but a simple paddle may be as simple as a plank. Does it need an adze? I do not think so: if Croatian Neanderthals were able to make a wood spear point and Catalan ones were able to create something that resembles a small paddle (a trowel?) without that tool, I must say that adzes are a mental barrier. Sure: they may be useful improvements for some tasks but they do not seem strictly necessary.

    We must understand that while we only find almost stones and bones, these make up maybe 10% of the daily equipment of your usual hunter-gatherer: woodwork, ropes, basketry, leather, bark, leaves, feathers... all are used by foragers on daily basis. Wood specially is a much used material, even where scarce.

    "I would just use my crude raft as a kickboard/paddleboard and rest on it when I got tired"...

    It is a possibility. But not in the rivers of Africa or the coasts of Northern Australia, full of crocodiles. You want to be out of the water. You also want to be out of the water in general because of many other risks (hypothermia, jellyfish, sharks, accidental loss of consciousness...)

    "The alternative of trying to make a decent paddle, when I am a poor woodworker, is too dismal to contemplate".

    I don't see why this should be so difficult, specially as foragers can't afford to be poor woodworkers. In the bush you have to do everything yourself (with family and friends, seldom alone): you must know every craft at least at a functional level. And that's what you learn when you are a kid instead of history, maths and grammar.

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  9. My view (my bias, honestly) is that our direct ancestors were much more intelligent than we ordinarily assume. That is why we are amazed at finding tools on islands, ancient bone flutes, art work, beautifully crafted projectile points, etc. The other presumption, that we should not credit them with any mental faculties until proven otherwise, is also simply a bias, but one that constantly has to retreat before new findings. It seems to me that beginning from the presumption that they were the same as us requires the fewest unproven assumptions. The farther in time we go back, or the further away from homo sapiens sapiens, the more questionable my bias may be. But my point is that we should not ever be too surprised to find evidence of technology of some kind. Culturally they may have been very different than we are, but they must have had very similar "software" to our own.

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  10. "Elephants can swim like 50 km and back, and they tow those that are tired. Humans can't..."

    Maju. We've been through this before. We're not just talking 'elephants' here. We're talking about 'faunal turnover'. So the fact that 'humans have been observed using all kind of aids, notably rafts and boats' is completely irrelevant. Unless you're claiming other species involved in the faunal turnover used such aids as well.

    "But instead you are looking to deny bonobos and our H. erectus cousins, even our own species, their true creative intelligent power, which we know they/we have".

    I have never claimed any such thing. It has always been you who have been so keen to distance yourself from our nearest relations, such as Neanderthal.

    "why would not be able to build a simple raft? Because Terry has decided so? That's no reason".

    Because, like the rocket, we had to learn how to make it over time.

    "I can't be sure but this is an immunity issue and seems that a quite radical one. Probably the mutant was a man (who that way excluded all other men, and all other male apes, australopithecines, etc.) from effectively reproducing with his daughters, granddaughters, etc".

    Sounds unlikely. It's far more likely that the gene was originally recessive, and so easily passed on to his or her offspring. It was only with some level of inbreeding that the double recessive combination was able to appear and spread through a relatively large population.

    "It is further evidence of pre-Sapiens navigation, three islands in three different parts of the world, different times, different species"

    Yes. And because each case is so isolated, in time, region and species, and similar evidence is not found in even the closest regions to those cases, there is very likely to be an alternative explanation than 'boats'.

    "Flores is three straits away from the Sundaland mainland (in Ice Age periods). Nothing can arrive there but crossing the sea".

    Not monkeys, rats, monitor lizards either. But they're clever enough to make boats, surely.

    "My guess is that groups of humans could go a long way across warm water just by some of them resting on a log while others hung onto the log and kicked. Easily believable that Homo erectus could do that".

    And logs probably carried other species to Flores as well. Not boats.

    "It is a possibility. But not in the rivers of Africa or the coasts of Northern Australia, full of crocodiles. You want to be out of the water".

    So would the rats and monkeys on the way to Flores.

    "Instead humans have been observed using all kind of aids, notably rafts and boats. And these are (normally) safe enough to bring your kids and even granny with you".

    And I agree they must have developed such transport in order to reach Australia.

    "I do not think either that sails are likely before (roughly) Neolithic".

    I agree. And the sail spread rapidly round much of the earth. Presumably by example, if not through closer interaction. One would expect any sort of boating technology to spread around the world too, but perhaps more slowly.

    "but a simple paddle may be as simple as a plank".

    When was the last time you tried to split a log into planks? Difficult. They didn't just turn up as driftwood in those days.

    "if Croatian Neanderthals were able to make a wood spear point"

    Making a spear point just involves knocking bits of wood off one end of a branch. A 'trowel is more complicated of course.

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  11. A couple more thoughts:

    "Faunal change may explain why people went after them, it may also talk of geological changes that made the island more accessible for a time..."

    I think the second in all those early cases.

    "I am a proud bonobo (sort of)".

    And bonobos don't have boats. They seem unable to cross the Congo.

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  12. "We've been through this before. We're not just talking 'elephants' here. We're talking about 'faunal turnover'".

    Sorry but I do not remember what "faunal turnover" other than elephants (Flores and its fauna are still East of Wallace Line AFAIK).

    "... like the rocket, we had to learn how to make it over time".

    Nonsense: the rocket was invented almost overnight. There are two technical jumps here: fireworks by Chinese in the Middle Ages and rockets proper by Germans in the 20th century.

    Evolution is largely NOT gradual but punctuated. In our techno-cultural case, that often implies individual or "compact" collective advances.

    But it's not really relevant because both models could be used to defend either position.

    "Not monkeys, rats, monitor lizards either".

    Monitor lizards swim very well and rats are known to have hitchhiked all kind of floating artifacts. What kind of monkeys? I have the impression that your set includes the most versatile of animals (and not just any animal).

    Anyhow, it'd be of interest if your alleged faunal turnover could be documented with dates. Do you have a reference? (I know how easily you can mix apples and oranges at your convenience).

    "When was the last time you tried to split a log into planks?"

    It can be easier or harder but, meh, if people can work yew (a kind of wood still preferred by carvers) into a spear point, you can make a paddle no doubt. I would say that the technical requirements of the spear point are quite greater than those of the paddle.

    It's relatively easy and fun for the patient woodworker to shape almost any piece of wood to his/her idea with the help of a mere knife (would be flake in Stone Age times). You can even create stone saws but you can more easily use wedges and such.

    "Making a spear point just involves knocking bits of wood off one end of a branch".

    I think it's very similar in concept to the flat part of a paddle. You need more than just one end of a branch and, in any case, you can even carve the damn paddle knocking bits of wood from a thicker branch or whatever. Patience moves mountains (and this is much more than just a saying).

    You can even work deer scapulas. Just a hunch.

    If paddles would not be available, I'd use sails before paddling with my bare hands (probably quite more effective) but my bet is wooden paddles.

    "And bonobos don't have boats".

    True. But H. erectus is a lot closer to us rocket-designer apes than to bonobos. And still a bit closer is the member of our own species: H. sapiens.

    And to all them you deny their ingenuity so stubbornly, even if evidence piles up in favor of archaic homo navigation.

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  13. "Sorry but I do not remember what 'faunal turnover' other than elephants"

    I'm sorry but you'll have to ask John Hawks where he got that information. I doubt that he would use the term to describe simply 'elephants'.

    "What kind of monkeys?"

    Macaques. Also deer and pigs, although humans may have introduced those species.

    "I would say that the technical requirements of the spear point are quite greater than those of the paddle".

    What?

    "But H. erectus is a lot closer to us rocket-designer apes than to bonobos".

    But boats would have to be invented somewhere along the line. And I seriously doubt that H. erectus had them.

    "And to all them you deny their ingenuity so stubbornly, even if evidence piles up in favor of archaic homo navigation".

    What evidence? There is none, only that which those with a preconceived opinion wish to regard as such.

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  14. "what faunal turnover"

    Hopefully you can track it down through this:

    http://johnhawks.net/node/17785

    I haven't had any luck tracking it except to see that tortoises were involved as well.

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  15. OK, so you have no idea of whether the "faunal turnover" included any animal other than elephants.

    I'll presume therefore that rats, macaques and even monitor lizards maybe were introduced by humans recently - though they are all very intelligent and adaptive species which can definitely take advantage of many odd circumstances and have made the journey themselves. In the case of monitor lizards maybe intently.

    "What?"

    You read it already. Quit the one-liners or I'll have to get hard-line with you.

    "What evidence?"

    Documented archaic human presence in three islands that can't be reached without boats. And this is just surely the tip of the iceberg.

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  16. "I'll presume therefore that rats, macaques and even monitor lizards maybe were introduced by humans recently"

    Not likely. Even the pig is probably native, as it's called the 'Flores warty pig':

    http://en.wikipedia.org/wiki/Sus_heureni

    And the rat is specifically Flores:

    http://en.wikipedia.org/wiki/Flores_Giant_Rat

    "Quit the one-liners or I'll have to get hard-line with you".

    To claim that 'the technical requirements of the spear point are quite greater than those of the paddle' is ridiculous.

    "Documented archaic human presence in three islands that can't be reached without boats".

    Just three islands widely spread through time, space and even species, and without any indication other nearby islands were occupied at the same time, is hardly evidence for use of boats. Try to come up with some actual evidence instead of just wishful thinking.

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  17. "To claim that 'the technical requirements of the spear point are quite greater than those of the paddle' is ridiculous".

    It's not: a spear point must be sharp, resistant, be retained by the flesh, have certain weight... a paddle just need to be flat (some hydrodynamics may help to save effort but are not strictly necessary and should come out with experience anyhow). It may be more work because it's a larger piece but not technically more complex, surely quite less.

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  18. "It may be more work because it's a larger piece but not technically more complex, surely quite less".

    I'll try to explain. But first of all have you ever cut down a tree, even with a chainsaw?

    "a spear point must be sharp, resistant, be retained by the flesh, have certain weight... "

    And involves cutting through a branch no more than 5 cms through. Once sharpened the point is scorched to harden it.

    "a paddle just need to be flat"

    And needs to be cut from a branch at least 20 cms through.

    "It may be more work because it's a larger piece but not technically more complex, surely quite less".

    It requires major effort to whittle away the amount of wood required. Or to split the branch into 'planks'.

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  19. "But first of all have you ever cut down a tree"...

    Axes exist since the Olduwayan, mind you: it's the most basic stone tool we know of (along with the grinder or chopper). I do not think they cut down big trees but small ones yes, and that's enough. If a beaver can, so can we.

    "And involves cutting through a branch no more than 5 cms through. Once sharpened the point is scorched to harden it".

    Spear point as in stone spear point that then attaches to a handle, not a mere fire hardened branch. Have you even looked at the model? It's not what you assume!

    "It requires major effort to whittle away the amount of wood required. Or to split the branch into 'planks'".

    Wisely using wedge technique it should not be that hard. As farmer, you may have worked out fence sticks from a log, right? You use two or three wedges and a sledge hammer and it's quite fast and even fun. They often come out quite flat. Of course they did not have these steel tools back then but they could well use stone ones or whatever other technique they found useful to save work.

    I see your point re. the paddle but I do not think it's any major, absolute obstacle. Where it exists, they may have used bamboo.

    With your attitude humankind would have never got anything done: you wave: "oh, oh, obstacle, get back" but humankind have advanced instead thanks to the people who say: "hm, challenge, I like it" and eventually come up with a solution.

    That's something I have learned from (quite enlightening) personal experience, that if you want something done you do it with patience and care: you cut a branch with cutlery, you set up a thick wet log in fire with a candle, etc. You get things done and not just complain of how hard they are.

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  20. "Axes exist since the Olduwayan, mind you"

    True. But it's doubtful they were hafted.

    "I do not think they cut down big trees but small ones yes, and that's enough".

    Not big enough to make a paddle.

    "Spear point as in stone spear point that then attaches to a handle"

    Who said anything about attaching a stone? I'm talking wooden spears. They were used long before hafting was invented.

    "You use two or three wedges and a sledge hammer and it's quite fast and even fun".

    Made of iron.

    "Of course they did not have these steel tools back then but they could well use stone ones"

    Stone ones are nowhere near as efficient. You're making things up.

    "With your attitude humankind would have never got anything done: you wave: 'oh, oh, obstacle, get back' but humankind have advanced instead thanks to the people who say: 'hm, challenge, I like it' and eventually come up with a solution".

    Maju. It's fair to assume that humans did not spread around the world like ink on a blotting paper. They moved through the most suitable habitat first. They avoided obstacles like desert, jungle and mountain until population pressure forced them into such zones. It seems obvious they were not able to move through islands easily until the very late Upper Paleolithic, and then primarily in the East.

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  21. You doubt all you wish if they were hafted or not, even the bare axe could serve to cut down a small tree with patience.

    "Not big enough to make a paddle".

    A grown baobab if need be, all that you need is patience and focus.

    "Who said anything about attaching a stone? I'm talking wooden spears".

    You do not know what you are talking about because I am the one who brought up this matter with due link (which includes a photo, that you have obviously not looked at).

    Go back through the conversation find the link and know what we are talking about: a distinct winged spear point but made of yew wood instead of your usual flint stone.

    "Stone ones are nowhere near as efficient".

    Maybe not but they used to be more efficient than mere copper: the appropriate kind of stone or wood can probably do a lot of good work. Bronze/steel may be better but that has indeed a recent dating.

    You lack practical imagination.

    "You're making things up".

    I'm wondering how would I do thinks given Olduwayan tech. I am not sure if H. ergaster/erectus/habilis/sediba used these ideas or others or none at all but at least I do not consider them incapable beings, as you seem to do. How could they adapt to the cold of high or northern Eurasia without creative skills similar to ours? You undervalue them a lot.

    Not to mention that you also undermine us, because the same that you reject for H. erectus, you reject for H. sapiens. According to you this conversation is surely not happening because the Internet is something that could not ever be even conceived...

    ... much less a boat.

    "They moved through the most suitable
    habitat first".

    I do not think there is most suitable habitat to us other than warm ones: we are tropically adapted species: that's our main adaption: lack of any hair worth mentioning (other than head hair) and the ability to sweat more than any other animal. Those are our adaptions, adaptions to equatorial heat.

    "They avoided obstacles like desert, jungle and mountain"...

    Desert is a major obstacle but jungle or mountain are not: they have food and water and other stuff we may need.

    "It seems obvious they were not able to move through islands easily until the very late Upper Paleolithic"...

    That is NOT what we see in the archaeological record: we see them in Sardinia, in Crete and in Flores (at least). And certainly we see our own species as far as New Guinea and Australia, as well as Japan, etc. since the end of the Middle Paleolithic.

    You are denying the facts.

    The mirrors in the Moon are evidence that we do have the ability to reach to the Moon now... even if we do not go often. Similarly the finger of Sardinia, the axes of Crete and Flores... are evidence that archaic people went there on their own will and means.

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  22. "A grown baobab if need be, all that you need is patience and focus".

    Yopu display a profound lack of practical sense. Do you have, or have you ever had, a practical job? I suspect not.

    "Go back through the conversation find the link and know what we are talking about: a distinct winged spear point but made of yew wood instead of your usual flint stone".

    There is a world of difference between a 'winged spear point but made of yew wood' and a paddle.

    "I do not think there is most suitable habitat to us other than warm ones: we are tropically adapted species: that's our main adaption"

    As I've said elsewherew, it is unlikel;y we moved across the surface of the earth like ink across blotting paper.

    "Desert is a major obstacle but jungle or mountain are not"

    You're not thinking logically here. Why are populations in jungles and mountains usually remnant populations left behind by wider migrations? Jungles and mountains are almost as great obstacles as are deserts.

    "That is NOT what we see in the archaeological record: we see them in Sardinia, in Crete and in Flores (at least)".

    You are the only one so confident that human presence on those islands necessarily means 'boats'.

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  23. I do not see "a world of difference": it's the very same concept at somewhat different scales.

    As for the blotting paper metaphore, it does not matter: even if people had preferences (which they probably did but were not the same for everyone), they eventually had to made hard choices and go to the second, third, etc. preferences because the first one was not available anymore in their known area.

    However there are absolute limites: open sea, too dry and too cold areas.

    "Why are populations in jungles and mountains usually remnant populations left behind by wider migrations?"

    Neolithic: Agrarian reasons: those areas are harder to farm. Military reasons: they are harder to conquer as well.

    It's obvious if you give it some thought instead of just reacting angrily as you do, without further thought.

    "Jungles and mountains are almost as great obstacles as are deserts".

    Not at all. High mountain is of course a major obstacle but milder mountains (and this depends mostly of cold, so it varies with latitude and not just altitude) can bee relatively good (or even locally prime) habitats (for example the Ethiopian highlands are quite good in their regional context).

    Jungle is not generally an obstacle for peoples with habituation, rather the opposite: it's protective and productive.

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