How did the Aborigines get to Australia?

Hi Portillo, From Message 386 on the That boat don't float thread:

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Yes, the pertinent question is how did all the species get to the places where they are found today, many with no known intermediates between their location and a single place where the ark was purported to land.

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How did koalas get to Australia without any koalas left in between?
How did they survive the journey without eucalyptus trees along the way and no evidence of them anywhere but Australia?

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And the question is not just one of getting from A to B, but also why that specific B for each species and no other - why no koalas in North America? Why no koalas in England?

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Why do we end up with the distribution pattern seen today?

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The question is more complex than just kangaroos/wallabies, but how did the whole Australian ecosystem get to Australia without leaving any evidence along the path?Same for South America and North America, Europe, Asia and Africa.Look at the Koala, it is a poor swimmer and it only eats eucalyptus leaves, and you only find (historical) evidence of koalas and eucalyptus trees in Australia.Science answer: they evolved there.Creationist answer: ? (careful - I've heard some doozies)Enjoy.

Hi Dr Adequate, Portillo, etc. I beg to differ.NOVA Online | Garden of Eden | Animation of Gondwana breakup

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We begin at 150 million years ago, when the Seychelles were still buried within the Gondwana supercontinent. Note that present-day coastlines are outlined in purple, while green areas represent land either above or below sea level. As Gondwana breaks up, watch for the birth of the Mascarene Platform, on which the Seychelles lie, about 65 million years ago. Observe India as it collides with Asia, leaving behind the so-called 90 East Ridge. Represented by the green line appearing to jut out of eastern India, the 90 East Ridge is a submerged mountain range that arose along a hotspot trail (much as the Hawaiian islands did). The animation continues 50 million years into the future, with the African Rift Valley opening up widely and India migrating well into Asia. Please note that these future projections are purely speculative and merely represent how tectonic-plate movements are currently trending.

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At the start of the animation you have S.America, Africa, India, Antarctica and Australia all grouped together -- and Asia is at the upper right, not part of the group.After they separate you see India collide with Asia.At the end of the animation you have Australia moving towards Indonesia, but not colliding with it.In between Asia and Australia is the Wallace Line:Wallace Line - Wikipedia

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The Wallace Line (or Wallace's Line) separates the ecozones of Asia and Wallacea, a transitional zone between Asia and Australia. West of the line are found organisms related to Asiatic species; to the east, a mixture of species of Asian and Australian origin is present. The line is named after Alfred Russel Wallace, who noticed this clear division during his travels through the East Indies in the 19th century. The line runs through Indonesia, between Borneo and Sulawesi (Celebes), and through the Lombok Strait between Bali and Lombok. Antonio Pigafetta had also recorded the biological contrasts between the Philippines and the Maluku Islands (Spice Islands) (on opposite sides of the line) in 1521 during the continuation of the voyage of Ferdinand Magellan, after Magellan had been killed on Mactan.

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The distance between Bali and Lombok is small, about 35 kilometers. The distributions of many bird species observe the line, since many birds do not cross even the smallest stretches of open ocean water. Some bats have distributions that cross the line, but other mammals are generally limited to one side or the other; an exception is the Crab-eating Macaque. Other groups of plants and animals show differing patterns, but the overall pattern is striking and reasonably consistent.

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Biogeography: Wallace and Wegener - Understanding Evolution

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Today Alfred Russel Wallace (left) is a prisoner of scientific parentheses, as in, "the theory of evolution by natural selection proposed by Charles Darwin (and also by Alfred Russel Wallace)." Yet Wallace was a great naturalist in his own right, particularly in the way he used evolutionary theory to interpret the natural world. In one of his most important applications, he helped found the modern science of biogeography the study of how species are scattered across the planet, and how they got that way.

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Patterns of species' ranges
Wallace had already accepted evolution when he began his travels in 1848 through the Amazon and Southeast Asia. On his journeys, he sought to demonstrate that evolution did indeed take place, by showing how geography affected the ranges of species. He studied hundreds of thousands of animals and plants, carefully noting exactly where he had found them. The patterns he found were compelling evidence for evolution. He was struck, for example, by how rivers and mountain ranges marked the boundaries of many species' ranges. The conventional explanation that species had been created with adaptations to their particular climate made no sense since he could find similar climatic regions with very different animals in them.

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Wallace came to much the same conclusion that Darwin published in the Origin of Species: biogeography was simply a record of inheritance. As species colonized new habitats and their old ranges were divided by mountain ranges or other barriers, they took on the distributions they have today.

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This map from Wallace's 1876 book shows his Oriental biogeographic region, broken into four subregions (outlined in red).

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Wallace had noted that reproductive isolation resulted in increased diversity of life -- not just evolution but speciation.The bottom red line surrounding "Indo-Malayan" and dividing it from the islands leading to Australia is Wallace's line.There was no land bridge between Asia and Australia.A good introduction to biogeography isThe Song of the Dodo: Island Biogeography in an Age of Extinction, by David Quammen
http://www.amazon.com/...ogeography-Extinction/dp/0684827123Enjoy.Edited by Zen Deist, : clrtyEdited by Zen Deist, : splingEdited by Zen Deist, : spling agin

Hi Granny Magda,Thanks for adding further to the story of Australia. The only footnote I would add, is that the modern marsupials on Australia all evolved after the separation, and isolation, of Australia.This certainly does not answer the question of how koalas, for example, could get from a central ark landing site to Australia.Enjoy.

Hi jar, Could be, but the typical creationist explanation is (a) that pre-flood geology differed and/or (b) the animals came to Noah so he didn't have to round them up.It is much more difficult to argue about leaving the ark being special conditions.Enjoy.

Hi foreveryoung, and welcome to the fray And North America and South America and Africa ...That would be the scientific explanation, not a creationist explanation. The problem for you is that this doesn't make the scientific explanation work for your brand of creationism (which sounds a lot more like old earth creationism or gap creationism than YEC).If you want to argue about the age of the earth, then I suggest you read and reply to Age Correlations and An Old Earth, Version 2 No 1 -- note that the issue of interest is the correlations between the various methods.Science is consistent and there are a lot of cross-correlations between a number of different sciences.If you think "... due to accelerated radioactive decay" is a viable argument, then you haven't really looked at the new problems you create that now need to be explained. See Are Uranium Halos the best evidence of (a) an old earth AND (b) constant physics?:

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Many people in this debate are familiar with the "problem" of Polonium halos, however this thread is not about Polonium halos, and any further mention is off topic (see PRATT CF201: Polonium Halos). Anyone wanting to talk about Polonium halos is free to start their own thread, and not clutter this one up, thanks.

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Where I am starting is from Dr Wiens:
Radiometric Dating

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The basic radiohalo principle is simple: radioactivity produces alpha decay, and the alpha particle have a certain energy (usually measured in million electron volts, MeV) based on the familiar e=mc² formula and the conservation of energy/mass (see ref):

M₁ = M₂ + mp + e/c²

Thus when you have isotopes decaying into other isotopes by alpha decay, the energy of the alpha particle is unique to that decay stage because of the unique before and after mass of the decaying isotope and the constant mass of the alpha particle.

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The halos require more than one particle to form as each one only makes a point on the ring. Thus uranium, with it's long half-life, takes "several hundred million years to form."

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Now the fun part: this is based on our knowledge of physics and the physical constants that tell us how things behave in the universe, so what happens if you have fast decay instead of old time?

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However, if the alpha has enough energy to surmount this barrier then it will regain that energy as electrostatic repulsion once it gets outside the range of the attractive strong nuclear force. One important consequence of this is that all alpha emissions have at least ~5 MeV energy. Furthermore, half-life is inversely related to decay energy.

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(bold for empHASis)

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Very simply put, if you change the decay rate, you change the decay energy, and the diameter of the halo changes.

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There should be no characteristic uranium halos with the unique energy of uranium alpha decay from fast decay.

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The existence of (common) uranium halos then is evidence that shows the physical constants have not changed while they were formed, and their formation in turn is evidence that the earth is old, at least several hundred million years old.

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Rapid decay means no uranium halos, but uranium halos are common, therefore no rapic decay.There are other problems, but uranium halos are objective empirical evidence that falsifies any hypothesis of rapid decay.Enjoy.

Hi Coyote, Yep.It also means that there would have been a large number of spontaneous natural reactors wherever uranium and other fissionable isotopes were found in the concentrations seen in the earth today: none of these deposits should exist, because they should have all gone through the melt-down sequence seen at Oklo:http://oklo.curtin.edu.au/

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This is one of the most fascinating stories in the relatively short history of Science and especially in the even shorter history of Nuclear Physics. In 1972 the very well preserved remains of several ancient natural nuclear reactors were discovered in the middle of the Oklo Uranium ore deposit.

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Since their discovery the Oklo reactors have been studied by many scientists around the world who have uncovered the answers to the following questions.

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• Where are the Oklo reactors located?
• When did the nuclear reactions occur?
• What caused the nuclear reactions to start?
• Why are these reactors worth studying?
• Who discovered the reactors?

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Here you can explore the answers to these and many other questions about the Oklo natural fossil reactors and investigate many other things about nuclear fission.

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With more rapid decay, the critical mass would be smaller, and there would be many such reactions occurring with smaller concentrations of fissionable materials.Curiously, the only evidence we have for such reactions is where there was sufficient fissionable mass to cause reactions the same as what we see in the world today.Therefore rapid decay did not occur.And, because of the byproducts of radioactive decay, and their relative amounts, we can date the Oklo reactors:http://oklo.curtin.edu.au/when.cfm

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Using a number of radioactive clocks the Oklo fossil reactors have been radioactively dated to be about 2000 million years old. The uranium in these reactors is thought to have come from the tiny amounts of uranium orginally scattered throughout the earth’s crustal rocks during its formation.

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That's 2 billion years old.Enjoy.

Hi again jar,We are essentially arguing passed each other. Surely you are familiar with ICANT's gondwanaland pre-flood concept? No water\oceans to cross, plus the flood wipes out evidenceof travel to the ark site. Creationists can, have, and will shrug off these questions.The problem that can't be shrugged off is how they get to their current locations from the ark.And if the fossil evidence is from the gondwanaland time, then how do the species get to the specific land masses that have their ancestral fossils? Most curious.Enjoy.

Hi NoNukes,Sorry to have confused you. Sadly, for you, opinion is incapable of altering reality. Curiously, critical mass is defined by the number of decay events within a given volume of radioactive material.Critical mass - Wikipedia

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A critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The critical mass of a fissionable material depends upon its nuclear properties (e.g. the nuclear fission cross-section), its density, its shape, its enrichment, its purity, its temperature and its surroundings.

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Changing the point of criticality

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The point and therefore the mass where criticality occurs may be changed by modifying certain attributes such as fuel, shape, temperature, density and the installation of a neutron-reflective substance. These attributes have complex interactions and interdependencies. This section explains only the simplest ideal cases

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• Varying the density of the mass

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The higher the density, the lower the critical mass. ...

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Enrichment means increasing the density of decaying material.Enriched uranium - Wikipedia

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Enriched uranium is a kind of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. ...

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Slightly enriched uranium (SEU)

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Slightly enriched uranium (SEU) has a ²³⁵U concentration of 0.9% to 2%. ...

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In other words the density of ²³⁵U in the lowest category of enriched material used in reactors is a little more than double what it is in nature.If your double the rate of radioactive decay, then that produces the same number of decay events in a given time period that would occur in twice the density of current fissionable isotopes compressed into half the current volume. It would be the same as enriching available ore to have twice the number of decay events.Result: a two-fold effective density of radioactive material. Uranium ore with this density of fissionable material occurs in the world today. As such ore did not cause fission events similar to Oklo, then such doubling did not occur.Curiously, to achieve anything close to a YEC model age, doubling the rate of radioactive decay is terribly insufficient: it would only mean reducing the age of the earth from 4.55 billion years to 2. 27 billion years.EnjoyEdited by Zen Deist, : clrty

Hi again NoNukes, No, enrichment means changing the ratio of fissile to non-fissile material to increase the proportion that is fissile compared to the proportion that is non-fissile.This increases the density of the fissile material within the combined mass. Do you think that fission is a completely separate process from decay? That they operate under different physical laws?Fission is just a form of decay: instead of alpha and beta particles, larger chunks are involved. What is the difference in the process between fissioning off a Helium nucleus (alpha particle) and a larger nucleus?What causes the neutron emission?Neutron emission - Wikipedia

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Neutron emission is a type of radioactive decay of atoms containing excess neutrons, in which a neutron is simply ejected from the nucleus. ...

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Curiously, beta decay leaves behind an extra neutron.

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Many heavy isotopes, most notably californium-252, emit neutrons among the products of a different radioactive decay process, spontaneous fission. ...

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Fission is a type of decay process.Spontaneous fission - Wikipedia

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Spontaneous fission (SF) is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units (u), spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses. ...

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As the name suggests, spontaneous fission gives much the same result as induced nuclear fission. However, like other forms of radioactive decay, it occurs due to quantum tunneling, without the atom having been struck by a neutron or other particle as in induced nuclear fission. Spontaneous fissions release neutrons as all fissions do, so if a critical mass is present, a spontaneous fission can initiate a self-sustaining chain reaction. ...

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The process that results in alpha and beta decay is the same process for spontaneous breakdown into nuclei larger than a Helium nuclei (alpha particle).You can't affect decay rates without affecting fission decay.When you reduce the nuclear binding energy or lower the barrier for radioactive decay to occur, and reduce the decay rate, you would increase the occurrence of all forms of radioactive decay, including fission.This means that the critical mass required to reach a sustained reaction is reduced. And to complete your analogy, now consider applying a match to wet newspaper and newspaper dowsed in gasoline.The level of enrichment needed to reach the point where the fission process becomes continuous or explosive is reduced, the amount of fissionable material to reach critical mass is reduced.Enjoy.

Hi NoNukes,First off, I am aware that you have worked in a nuclear reactor.That does not mean that you have worked through the question of what you need to do to increase the rate of decay, and then determined how that affects the rest of the (atomic) world. Enrichment Definition & Meaning | Dictionary.com

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en•rich•ment - noun
1. an act of enriching.
2. the state of being enriched.
3. something that enriches: the enrichments of education and travel.

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Fine. I was using action while you are using state, but we can use enriching for clarity to reduce confusion. The point is the same. Curiously, the natural reactors at Oklo were started by spontaneous fission. The relative proportions (natural state of enrichment) today do not allow this, but they did in the past:http://oklo.curtin.edu.au/what.cfm

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Uranium Isotopes Today
For every 100,000 atoms of U only 720 are ²³⁵U atoms. Since ²³⁵U is the isotope of U that is easiest to fission most man made reactors require ‘enriched U’ — U in which the relative amount of ²³⁵U is increased to about 3000 atoms per 100,000 atoms (i.e. 3%).

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Uranium Isotopes 2000 million years ago
At Oklo, as on the rest of the earth and solar system, 2000 million years ago the relative abundance of U-235 was 3000 atoms per 100,000 atoms.

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This is one of the major reasons why nuclear fission started.

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Natural fission reactors cannot form today because there is insufficient ²³⁵U in natural U.

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The natural level of enrichment in the ore 2000 million years ago was the same as your man-made enriched uranium used in nuclear reactors today.The processes that are documented in the evidence left at Oklo show that they underwent fission similar to reactors today, with no change of the physical laws governing the behavior of radioactive elements from then to now. It does not double the number of targets, but it does double the number of bullets, thus doubling the exposure of the targets, with the effect being the same as doubling the enrichment in material today. This would also be akin to providing a neutron reflector around the material.http://nuclearweaponarchive.org/Library/Fission.html

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The stability of an atomic nucleus is determined by its binding energy - the amount of energy required to disrupt it. Any time a neutron or proton is captured by an atomic nucleus, the nucleus rearranges its structure. If energy is released by the rearrangement, the binding energy decreases. If energy is absorbed, the binding energy increases.

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The isotopes important for the large scale release of energy through fission are uranium-235 (U-235), plutonium-239 (Pu-239), and uranium- 233 (U-233). The binding energy of these three isotopes is so low that when a neutron is captured, the energy released by rearrangement exceeds it. The nucleus is then no longer stable and must either shed the excess energy, or split into two pieces. Since fission occurs regardless of the neutron's kinetic energy (i.e. no extra energy from its motion is needed to disrupt the nucleus), this is called "slow fission".

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By contrast, when the abundant isotope uranium-238 captures a neutron it still has a binding energy deficit of 1 MeV after internal rearrangement. If it captures a neutron with a kinetic energy exceeding 1 MeV, then this energy plus the energy released by rearrangement can over come the binding energy and cause fission. Since a fast neutron with a large kinetic energy is required, this is called "fast fission".

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In nuclear reactions today some neutrons are lost from the chain reaction due to neutron capture without fission, due to the binding energy level of the various isotopes.Curiously, the binding energy also affects the decay rate, and increased decay rate means that the effective binding energy of the atom\isotope is reduced.With lower binding energy, neutron capture is more likely to exceed the (lower) binding energy limit for fission to occur, with the result that induced fission would occur more often: less critical mass is needed.In addition, the numbers of neutrons resulting from fission would also increase:

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(ibid) The nuclei of these isotopes are just barely stable and the addition of a small amount of energy to one by an outside neutron will cause it to promptly split into two roughly equal pieces, ... and several new neutrons (an average of 2.52 for U-235, and 2.95 for Pu-239).

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Amusingly, neutrons exist in integer quantities, not fractions. There is variation in the number of neutrons produced from individual events.The number of neutrons produced is also related to the binding energy that controls decay rates. Faster decay = more neutrons produced by induced fission = less critical mass.Enjoy

Hi foreveryoung,See Message 91 on Are Uranium Halos the best evidence of (a) an old earth AND (b) constant physics? for my replyEnjoy.Edited by Zen Deist, : mid not tidEdited by Zen Deist, : moved off-topic post

Per AdminModulous (Message 64)I have initiated a new thread at Decay rates, change, and atomic stability, Message 1.oops - preempted. See Message 3 of Spontaneous fission, decay rates, and critical massEnjoy.Edited by Zen Deist, : revised link

Hi dwise1, Hence causing what is known as the Wallace Line that divides species on one side from those on the other (except for those that could fly or swim the distance).

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Alfred Russel Wallace, the so-called father of animal geography, formulated his ideas on evolution by natural selection while observing and collecting wildlife in the islands of Southeast Asia. He was particularly impressed by the sudden difference in bird families he encountered when he sailed some twenty miles east of the island of Bali and landed on Lombok. On Bali the birds were clearly related to those of the larger islands of Java and Sumatra and mainland Malaysia. On Lombok the birds were clearly related to those of New Guinea and Australia. He marked the channel between Bali and Lombok as the divide between two great zoogeographic regions, the Oriental and Australian. In his honor this dividing line, which extends northward between Borneo and Sulawesi, is still referred to today as Wallace's Line. (See the map below.)

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You can also see this subduction zone trench formation continue along the east side of the Philippines, and another to the east that is the Mariana trench, the deepest part of ocean in the world. If you want a land bridge here, you are going to need to wait for a while ...Enjoy.Edited by Zen Deist, : lastlineEdited by Zen Deist, : graphy not ology

Hi Portillo, Actually there is a very well recorded history by people living in Spain and Southern France 32,000 years ago regarding life at that time.

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Cave painting

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Cave paintings are paintings on cave walls and ceilings, and the term is used especially for those dating to prehistoric times. The earliest European cave paintings date to the Aurignacian, some 32,000 years ago.[1] The purpose of the paleolithic cave paintings is not known. The evidence suggests that they were not merely decorations of living areas, since the caves in which they have been found do not have signs of ongoing habitation. Also, they are often in areas of caves that are not easily accessed. Some theories hold that they may have been a way of communicating with others, while other theories ascribe them a religious or ceremonial purpose.

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Nearly 350 caves have now been discovered in France and Spain that contain art from prehistoric times. Initially, the age of the paintings had been a contentious issue, since methods like radiocarbon dating can be misled by contaminated samples of older or newer material,[2] and caves and rocky overhangs (parietal art) are typically littered with debris from many time periods. But subsequent advances made it possible to date the paintings by sampling the pigment itself and the torch marks on the walls.[3] The choice of subject matter can also indicate date, as for instance in the reindeer at the Spanish cave of Cueva de las Monedas which place the art in the last Ice Age.

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The oldest known cave art is that of Chauvet in France, the paintings of which may be 35,000 years old according to radiocarbon dating, and date back to 33,000 BCE (Upper Paleolithic).[4] ...

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These paintings depicted the historic varieties of the animals of that time, some in great anatomic detail which are identifiable from the fossil record (which also extensively records the history of life on earth).Then there is the rock art in Australia (to get vaguely back to the topic):

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Petroglyphs - Pictographs - Cave Paintings - Geoglyphs

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Ancient rock art's colors come from microbes BBC - December 28, 2010
A particular type of ancient rock art in Western Australia maintains its vivid colors because it is alive, researchers have found. While some rock art fades in hundreds of years, the "Bradshaw art" remains colorful after at least 40,000 years. Jack Pettigrew of the University of Queensland in Australia has shown that the paintings have been colonized by colorful bacteria and fungi. These "biofilms" may explain previous difficulties in dating such rock art.

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A recorded bit of history from 40,000 years ago in Australia.Enjoyps -- these caves and rock paintings were never flooded . . .Edited by Zen Deist, : nested quotes for full contextEdited by Zen Deist, : added australia rock paintings

Hi Portillo,To add to what the others have said: Not a stream but a seabed:Ancient Sea Levels

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North America during the late Cretaceous

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Western Interior Seaway - Wikipedia

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The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period. It was 2,500 feet (760 m) deep, 600 miles (970 km) wide and over 2,000 miles (3,200 km) long.

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The Seaway was created as the Farallon tectonic plate subducted under the North American Plate during Cretaceous time. As plate convergence proceeded, younger and more buoyant lithosphere of the Farallon Plate started to become subducted. This caused it to subduct at a much more shallow angle, in what is known as a "flat slab". This shallowly-subducting slab exerted a traction on the base of the lithosphere, pulling it down and producing "dynamic topography" at the surface that caused the opening of the Western Interior Seaway.[1] This depression and the high eustatic sea levels existing during the Cretaceous allowed waters from the Arctic Ocean in the north and the Gulf of Mexico in the south to meet and flood the central lowlands, forming a sea that transgressed (grew) and regressed (receded) over the course of the Cretaceous.

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Oceans of Kansas Paleontology

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OCEANS OF KANSAS PALEONTOLOGY
Fossils from the Late Cretaceous Western Interior Sea

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There are also fossils from the same time period of land animals, and of nests with dinosaur eggs:Error 404 | Emory University | Atlanta GA

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One of the more spectacular dinosaur fossil finds of recent years was of a Late Cretaceous specimen of Oviraptor that was found in a sitting position directly over its nest. This find, a wonderful combination of trace fossils and a body fossil, represents one of the most compelling pieces of evidence for brooding behavior in dinosaurs. This fossil find is currently on display at the American Museum of Natural History in New York and was illustrated in a National Geographic article.

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Nests that would have washed away in a flood.Enjoy.