Human Evolution on Trial - Change

Human Evolution on Trial - Change

The only thing constant is change. Change may be rapid but is more usually gradual. It can also be large or small. Change leads to variety through both time and space. Changes in the rate and size of change have given rise to the phenomenon known in evolution as “punctuated equilibrium”, periods of large and rapid change separated by periods of very little change.

New Zealand

New Zealand is a young country both geologically speaking and in relation to human history. It also occupies a small space on planet earth. This combination of factors makes it a convenient place to start any examination of the past.

The jury will find the patterns we discover there have a much wider relevance than just for New Zealand or even just for modern humans though. All the patterns and ideas the defence presents here will pop up regularly during the rest of this case in favour of the defendant.

New Zealand consists of two main islands, and several smaller ones, which stretch from latitude 48° south to latitude 34° south with some small islands beyond these latitudes. Most of the country’s underlying rock, or skeleton, consists of material laid down on the sea floor between the beginning of the Permian geological period (260 million years ago) and, halfway between then and now, the end of the Jurassic (130 million years ago). Over time the material was compressed, heated and hardened by the weight of the sea, chemical reactions and heat from the earth’s core. Earth movements eventually pushed up this material and made New Zealand’s skeleton. The skeleton was then overlain with younger rock eroded off this skeleton as well as with some volcanic material.

That all this change is still going on is shown by the fact New Zealand suffers many earthquakes and has several active volcanoes. In fact Australians often call us “The Shaky Isles”. The defence will provide the jury with a short history of the earth and return to this side of things in Part III (“Time” and “Long Ago”).

New Zealand has been isolated in the southwest Pacific Ocean since the southern continent of Gondwanaland started breaking up during the Cretaceous more than 65 million years ago. The nearest continent is Australia, 2000 kilometres to the west, and much of New Zealand’s plant and animal, and especially bird, life has arrived across the ocean from there. Several bird and insect species have arrived through their own efforts even in the two hundred years since Europeans got here. But there is biological evidence of ancient island connections to the northwest, via both Lord Howe and Norfolk Islands, to New Caledonia and probably even further north (Stevens 1985).

Actually some of our birds and especially plants have been here since the ancient continent broke up. For example we share, or used to share, large flightless birds with Australia, New Guinea, Africa, Madagascar and South America. The New Zealand representatives of this group have been called “moa”. They died out as recently as five hundred years ago. Several small members of this group, the kiwis, still survive in New Zealand but they too seem to be rapidly dying out.

Destruction

The arrival of humans caused a major change in the New Zealand environment. In “Extinctions” the defence will show that this has been the pattern throughout the world. Elliot, Manighetti and Carter (2003) have produced a pollen profile that shows a permanent drop in the amount of forest tree pollen from between about 1000 and 1200 AD, the generally accepted time of Polynesian arrival. The profile does show human induced fires first occurred on the east coast of the North Island about 1500 years ago. Other evidence suggests the Polynesian rat (Rattus exulans) may have also been present in New Zealand by then. The pollen profile shows the forest then soon recovered quite significantly although not quite to its previous level.

The evidence for the presence of humans in New Zealand before a thousand years ago may indicate the arrival of all-male fishing parties lost in storms or small groups of migrants who failed to leave descendants. You will later see that the source of these migrants was presumably Western Polynesia (Fiji or Tonga) but there is actually no evidence for this other than possibly some rat nuclear DNA (King 2003). In fact mitochondrial DNA evidence from Polynesian rats now living on offshore islands around New Zealand shows they are genetically closest to those from Eastern Polynesia; the Cook and Society Islands (Lisa Matisoo-Smith quoted in Howe 2003). This suggests the evidence for their early arrival may have been misinterpreted but you saw in “Pedigrees” [Populations] that mtDNA lines can die out for one reason or another.

Although some inhabitants of New Zealand claim more ancient ancestry within the country overall the evidence doesn’t support the presence earlier than about 1200 AD of any people who left descendants. Some members of the prosecution might claim any earlier settlers in New Zealand were able to live completely in harmony with their environment and that is why we can find so little evidence for their existence. The defence will offer more evidence on the subject in “Extinctions” and show this is most unlikely. If it were so they would be the only humans in the whole history of the earth to have achieved this harmony. Of course it is possible very small numbers of earlier inhabitants survived in New Zealand but they were on their way to extinction by the time the later people arrived (possibly through inbreeding and we’ll look at this next). An increase in fire, extinction of birds, carbon dating of human artifacts and the earliest stone tool types all date to more recently than 1200 AD (McGlone et al in Sutton 1994 and King 2003).

But let’s not get carried away with how special humans are. The environment usually changes, sometimes in an extreme manner, with the arrival of any new species.

The permanent settlers who arrived in New Zealand about one thousand years ago probably maintained contacts over the whole country (Sutton 1994 and King 2003). James Belich (1996) provides a good argument that a sizeable migration reached New Zealand and it spread virtually instantly around the desirable parts of the coast. He suggests that for a people who had just travelled over the Pacific Ocean a few trips around the coast of New Zealand was nothing (and see also Bellwood 1978). The relatively sheltered East Coast provided the main trade routes, seals and moa provided abundant food and everyone was happy…

…Until the most easily exploitable resources ran out.

Increasing Population + Diminishing Resources = Strife + Selection

Studies of both prehistoric and modern hunter-gatherer groups show that life is short and women have only three or four children each (see for example Houghton 1980). But these studies are not done on populations moving into previously uninhabited regions.

The population numbers of any species usually grows to the maximum possible for the resources available. As James Burke (1978) says, in relation to humans in Medieval Europe, “When times are good the population rises, and sooner or later, it rises too far”. The population growth in New Zealand could have been very rapid with adequate food, no overcrowding and no predators. Allowing a generous 25 years per generation and women having as many as ten children, half of whom would be female, the population potentially could have reached epidemic proportions in 200 years (over three quarters of a million starting with even just one couple). Rosalind Murray-McIntosh’s research on mitochondrial DNA (quoted in Howe 2003) indicates at least seventy women arrived in New Zealand, i.e. at least 200 people.

Evidence from the teeth of skeletons shows that by about 1500 AD life in New Zealand had become more difficult. Moa, along with seal colonies on easily accessible parts of the coast, had dissappeared. The diet of prehistoric Maori changed from seal and moa meat to an increase of fern root (Houghton 1980). The culture then changed and we get fortified settlements (Howe 2003) and division into separate groups, tribes.

Tribes

The word tribalism can mean different things to different people but I suggest we say it is the grouping of humans into larger units than simply families. A tribe is therefore the largest group that any particular individual considers him or her self as belonging to. It can vary from less than two hundred up to the size of a nation. Tribes are held together by shared culture. The defence showed earlier (“Mythconceptions”) that our beliefs are part of our culture. We will return to this side of things in Part V (“Culture”). In modern society, especially cities, the tribal groups we identify with can change almost from hour to hour but until recently tribes were a more stable concept. Humans, especially infant humans, survive best, or even only, as members of a cultural group or tribe. Children accept the culture and mythconceptions of the tribe they grow up with as normal. This is just as well. Life would otherwise be too complicated for most of us to cope with. It also means culture usually changes quite slowly. But elements of it can change quite rapidly when children associate mainly with their own age group during their schooling.

Tribalism is therefore part of culture and seems often to be strengthened in response to limited resources. Tim Flannery (2001) has suggested cultural diversification and tribalism developed in North America also as a result of the depletion of resources after the initial colonisation by the ancestors of the American Indians.

We might regard tribalism as the first step on the road to speciation, the evolution of life into the reasonably discreet units we call “Species”. Many animals such as dogs, rats and especially birds display tribalism and it is a learned behaviour even there. Young birds are imprinted soon after hatching with the form, colour and song of their parents. This means they usually mate with the members of their species similar to them even though they may be quite capable of mating with others. Frank Gill (1998) has stated...

“Projected to its full conclusion, this line of thinking suggests that speciation in birds is as much a cultural phenomenon as it is a genetic phenomenon”. Behaviours that lead to speciation (or tribalism) are called “isolating mechanisms” and many behavioural characteristics are genetically inherited (Jones 2000). The whole phenomenon is much more widely spread than just among birds but they do provide interesting evidence.

Galapagos Finches

The defence suggested in “Conception” [The Chinese Drover’s Clever Dog] we should assume there is one set of biological rules for the whole of nature including humans unless it can be proved otherwise.

Throughout nature during times of plenty and when numbers are expanding the boundaries become porous. Everyone parties on. Tribalism decreases and even what have been recognised as being different species may breed together. For example two kinds of Geospiza, or ground finch, from a single island in the Galapagos sometimes breed together in times of plenty (Weiner 1995). Normally the different kinds specialise in exploiting different elements of the environment. Some have a large beak and others have a small beak depending on what food they specialise in. The finches, taken together, form a double bell curve for this characteristic. Breeding is usually confined within each of the two types, big beaks breeding only with big beaks for example. Hybrids are at a disadvantage compared to the specialists. This has led to the development of two apparently separate kinds or species. But when the environment changes dramatically, such as during El Niños when rainfall increases, population numbers increase rapidly and the two separate species of finch often breed together. Hybrid individuals with middle-sized, unspecialised beaks are able to survive and breed. The two bell curves tend to merge. Genes swap between the two kinds. With the return of difficult conditions the types separate again each specialising in their particular ecological extreme. It seems that in general specialisation, tribalism and separation are greatest at times of environmental stress.

Interestingly, a similar thing has been shown to happen with human society. As long ago as 1915 John Dewey (1966) claimed different classes and social groups mix with each other more during expansive economic periods. Presumably he agreed they tend to become isolated when times are difficult. And in his book “Mapping Human History” Steve Olson (2002) claims immigrants to France over the last fifty years have been assimilated into French society more effectively during times of better economic performance. The balance of nature is very complex and constantly changing. The defence will return to this idea many times during this case in favour of Human Evolution.

It is possible that at times during human existence we have not been tribal. The numbers able to survive the worst of times determines the numbers of any particular species in any region. The human population may have been kept in check by seasonal or periodic food shortages, predators, environmental disasters such as floods, droughts etc. and even genetic diseases. It might have been a major and happy occasion when one family group met another during times of plenty. It is probably fair to say much gene flow would have occurred. The evidence indicates that throughout history the introduction of new technology has led to times of plenty. Times of plenty promote population expansion and (at least to some extent) the breaking down of tribal barriers.

But during the last few thousand years for most of us our greatest enemy has usually been each other. As resources become fewer creatures divide into closed groups. With hard times the Maori of New Zealand eventually grouped into tribes (King 2003). These tribes may have developed from divisions going back to the arrival of different canoes during the original migration to New Zealand, as oral tradition states, but to consider different tribes or “Iwi” were discrete, genetically isolated, populations is wrong. Maori myth is full of stories about people moving to live somewhere else. Much inter-Iwi marriage (pdf) occurred, especially in the upper classes. Regional differences did develop, though, and some people may be referred to as looking typically Tainui or Ngapuhi etc, though these differences are little more than family resemblances. It is also possible to tell where a native speaker of Maori comes from by their dialect and most of us are aware of the regional dialects of Britain and Ireland.

Variation Through Space

Different tribes or Iwi are actually the result of geography.

Of course throughout the world families living close to each other have always bred together and formed alliances based on common ancestry, sometimes mythical. Geographic boundaries isolate groups. Mountain ranges, especially heavily forested ones, or large swamps, isolated the various populations within New Zealand. They provided boundaries for the various tribal districts or “rohe”. For example Ngati Wai are from Northland’s East Coast. The heavily forested Puhipuhi hills and the Hikurangi Swamp separate them from Ngati Hine. The Tutamoe Range and Waipoua Forest separate Ngapuhi from Ngati Whatua (if Te Roroa are considered to be part of Ngati Whatua) though they come into contact around the south head of the Hokianga Harbour. Ngati Kahungunu are isolated by the Ruahine and Tararua Ranges and so on. You will later see the boundaries between many species are also geographic.

Variety, or difference, is a product of change through time and space and is not just confined to biology. It is even demonstrated by basic economics. The rich get richer and the poor get poorer. This used to be justified by the expression “survival of the fittest”; a term first used in 1852 by Herbert Spencer while he was sub-editor of the paper “The Economist”. In economics the concept obviously leads automatically to monopolies but most economists still prefer to keep quiet about that (Saul 2006).

The passing of time leads to greater change and so to greater variety. But Maori may not have lived in New Zealand long enough, or the country may not have been large enough for them to develop into tribes of the American Indian type. For example a single Maori language was spoken throughout New Zealand (King 2003) but the pre-European population of America shows a much greater level of variety. Apart from those of the far northwest, most languages of the American Indians are possibly related to each other and may have an ancient common origin (Greenberg and Ruhlen 1992). But subsequent internal migrations mean that individual tribes do not always understand their neighbours’ languages.

Africa provides an example of even greater variety of population. When I travelled in West Africa I could generally tell whether a person was Wolof or Mandinka by their features and the sound of the language even though I couldn’t actually understand either language. This is more than I can do for most national groups in Europe, but humans are presumed to have been in Africa longer than anywhere else and so differences have had longer to develop.

You will find throughout this case that languages, beliefs, species, and even individual genes, have all separated into regional varieties as they have spread around the world (for example “Pacific Population” [Mixing], “Culture” [Evolution of a Religion], “Species” [Difference], and “MtEve”[The Trees]).

Variation Through Time

Most Iwi or tribes in New Zealand trace their ancestry back to a particular individual. And so they are more like Scottish clans than they are like American Indian or African tribes. It is probably no accident groupings of Maori families or “Hapu” are referred to as Iwi. Iwi also means bones. Hapu (clan) means pregnant. While we’re on that subject whenua, land, also means placenta.

A claim to have descended from a particular ancestor usually gives an individual the right to live in a particular district or rohe. Sometimes it is suggested burial rituals in human culture may have first developed from a desire for descendents to stake a claim to a particular territory (Cunliffe 1994). As early as late “Middle Paleolithic” (paleao – old) Neanderthal times (about 40,000 years ago) there is controversial evidence for ritual burial (D’Errico 2003). But with the development of larger populations and the diversification of cultures during the “Upper Palaeolithic”, from about 35,000 years ago, the evidence is definite. Before this time human groups may have been more mobile.

But we can classify humans into a hierarchy of divisions or groups depending on the closeness of relationship, each level containing progressively more members. These groups make up a continuum. As in a pedigree numbers increase as you move to the right.

Individual / Family / Whanau / Hapu / Clan / Iwi / Tribe.

Membership of divisions further to the right indicates a more ancient common ancestry, progressively more likely to be based on mythconceptions.

Genetic similarities can be used to indicate close relationships at the left-hand end but beyond the right hand end, and often before then, genetic differences become regional rather than tribal. For example, as you saw in “The Human Star” [A Cline], the main genetic difference within the people of Europe shows up as a simple genetic gradient or cline from the northwest to the southeast despite the complicated distribution of different races and language groups (Cavalli-Sforza 1995). Even within North America and Australia the main gene variation of the pre-European inhabitants forms a cline and the various tribes cannot be distinguished genetically. Breeding is usually between near neighbours, or at least it was before the development of modern transport such as aircraft and even the bicycle.

The defence will now show the jury a diagram of these connections from the opposite point of view. It is like an individual’s family tree. The various lines all reach the bottom of the diagram but this would be very difficult to show.

Because languages change over time they too display degrees of separation. They evolve. The English language has actually changed considerably even in the short time since I was a child. It has taken on new words and expressions and many words have changed their meaning. The wave theory of genetic, cultural and technological evolution tells us that languages expand as waves. Although they usually mix with other languages they can also be arranged in the form of a family tree. We’ll later use this idea to help us follow human migration. The defence will even argue that genes spread in much the same way languages do, but by no means always together.

The evolution of languages can also tell us about evolution in general. Regional or spatial language variations start to develop with dialect being the first, grading in time to differentiation into separate languages within a particular language family. It can be very difficult to define the boundary between languages within a group though. For example the people on different islands in Polynesia speak different dialects and speakers of some dialects cannot understand some other dialects. The relationship is not simple as Rarotongans can usually understand much of New Zealand Maori but changes in the languages make it very difficult for some speakers of Maori to understand Cook Islanders. The relationship between species is not simple either, as the defence will later show.

The language we speak is part of our culture. Culture, including language, myths, clothing, art, music, sport and religious beliefs can serve to unite groups (even different tribes or races) and can promote gene flow.

But culture can also divide groups and obstruct gene flow. It usually relies on accentuating exclusiveness and division, a “them and us” philosophy. (Gene flow usually occurs even in this situation though). In other words culture can lead to differences that are apparent rather than real.

Culture and technology can travel further and faster than genes and there are many examples of groups adopting at least some elements of a different culture and technology. In fact New Zealand provides a good example of the mixing of two languages, two cultures, two technologies and two gene pools.

European Migration

The arrival of Europeans and the various animals and plants they brought with them led to yet another major and rapid change in New Zealand’s environment. History records that in 1642 the Dutchman Abel Tasman was the first European to see New Zealand but it is fairly likely Portuguese or Spanish sailors had already done so. It was Captain Cook’s voyage in 1769 that brought New Zealand to the attention of Europeans though. Sealing and Whaling ships soon visited and bases were established around the coast. Traders, escaped or released convicts from Australia and general adventurers then arrived followed by European missionaries. European men were readily accepted into Maori society because they brought in new technology (King 2003). Missionaries’ wives were probably the first European women to live in New Zealand but European women didn’t arrive in the country in any numbers until after 1840.

Until that time gene flow between the two human populations in New Zealand was almost entirely between European men and Maori women. In fact cultural factors meant Maori men didn’t contribute many genes to the European side of the population until long after that time. By then many Maori people already had some West European genes and spoke an imported language, English.

The English language itself is part of the German group and is a product of the Anglo-Saxon movements into England that started about 1600 years ago. This was not an instantaneous change either and it may have taken up to 300 years for English to replace any previous languages in England (Davies 2001). In fact there is a great deal of evidence to show much of the original population survived. This all goes to show that culture, including language, doesn’t necessarily coincide with chromosomes and DNA.

The defence will mention many migrations throughout this story and they should all be regarded as being similar to the movement of Europeans to New Zealand, Anglo-Saxons to England or the various groups into Egypt (“Mythconceptions” [Modern Myths]). A reasonably gradual process including mixing with the original population, usually at first by incoming males with resident females, a gradual mixing of genes and the eventual dominance of one language over the other, not always by the incoming one. Total population replacement is very rare. The movement of Europeans into New Zealand was fairly rapid because of modern transport. It was also complicated by the loss of a number of the indigenous population through internal wars, introduced diseases and the Victorian cultural attitudes of the immigrants.

New Zealand provides useful evidence for the defence case. We have at least two groups who can definitely be called different races with different cultures who are mixing genetically. One language is replacing the other, although words from the original language are being adopted by the more recent arrivals. International communications in one of these languages is hindering this exchange and during prehistoric times the whole process may have been more balanced. Languages too are able to form hybrids. Mixed languages are called “Creoles” but usually just one language dominates and it simply borrows words from the other (Jobling et al 2004). Any combined language always uses at least the basic elements of just one of the parent languages. Languages are classified by examining these basic elements because individual words can zoom around the world.

Today most New Zealanders have genes from a variety of ancestors; Ngapuhi, Ngati Wai, Wai Taha, Scottish, English, Chinese, Pacific Islanders etc. and what we can call Dalmatians or South Slav. In other words a mixed gene pool. The jury will eventually see it had been this way with their ancestors even before they left wherever it was they left to come here. But if somehow New Zealand became isolated for many generations, or several hundred years, the mix would eventually produce a new race with a new culture and language. Within that race people in the northern and eastern regions of the North Island would tend to have darker skin compared to those in the South Island.

They will have a higher proportion of Polynesian genes. Some Y-chromosme and mitochondrlal DNA lines will have died out but the majority of surviving lines would probably descend from European ones. Remember that in just 250 years time each individual’s pedigree will contain a list of over one thousand people alive today.

It is often said “the more things change the more they stay the same”. The defence will argue races and cultures have always developed in exactly the way New Zealanders have. In fact the pattern stretches right back to at least as far as our origin as a species. Human groups in contact with each other have always produced hybrids (crossbreeds) through gene flow. Homo erectus (“man erect” and see “First Humans”) may have been well named.

The jury will eventually see population movements have been continuous during Human Evolution. But we will need to brush up on genes before the defence can use the Polynesians’ evolution to help explain the evidence in favour of the defendant.

See next :: Human Evolution On Trial - 'Hybrid Vigour And Inbreeding'

Witnesses Called

Belich, James (1996) Making People. Penguin Press, Auckland.

Bellwood, Peter (1978) Man’s Conquest of the Pacific. Collins, Auckland.

Burke, James (1978) Connections. Macmillan, London Ltd.

Cavalli-Sforza, Luigi Luca and Cavalli-Sforza, Francesco (1995) The Great Human Diasporas. Addison- Wesley

Cunliffe, Barry ed. (1994) The Oxford Illustrated Prehistory of Europe. Oxford

University Press, Oxford.

Davies, John (2001) The Celts. Cassell and Co., U.K.

D’Errico, F. (2003) The Invisible Frontier: a Multiple species Model for the Origin of Behavioral Modernity. (pdf) Evol. Anthrop.12, 188[-202.

Dewey, John (1966) Democracy and Education. The Free Press, New York.

Elliot, M., Manighetti, B. and Carter, L. (2003) Dating the Human Colonisation of New Zealand. Proceedings of the New Zealand Geographical Society.

Flannery, Tim (2001) The Eternal Frontier. Text Publishing, Australia.

Gill, Frank B. (1998) Hybridization in Birds. (pdf) The Auk, Vol. 115 No 2 April.

Greenberg, J. and Ruhlen, M (1992) Linguistic Origins of Native Americans. Scientific

American, 267 –94-99, Munn and Co., New York.

Houghton, Phillip (1980) The First New Zealanders. Hodder and Stroughton, Auckland.

Howe, K. R. (2003) The Quest for Origins. Penguin, New Zealand

Jobling et al (2004) Human Evolutionary Genetics. Garland Science, New York.

Jones, Steve (2000) Almost Like a Whale. Anchor, London.

King, Michael (2003) The Penguin History of New Zealand. Penguin Books, New Zealand.

Olson, Steve (2002) Mapping Human History. Houghton Mifflin Company, New York.

Saul, John Ralston (2006) The Collapse of Globalism. Penguin Books, England.

Stevens, Graeme (1985) Lands in Collision. Science Information Publishing Centre,

Wellington.

Sutton, Douglas G. ed. (1994) The Origins of the First New Zealanders. Auckland University Press, New Zealand.

Weiner, Jonathan (1995) The Beak of the Finch. Random House, London.