Changing the way we look at the world
Paradigm Shifts of the past
There have been many paradigm shifts as humans tried to understand the universe, including:
Geocentrism to Heliocentrism
In 1610 Galileo pointed his telescope at Jupiter and observed the orbits of four of its moons. He was convinced that if there was a force (which we now call gravity) that could keep the moons of Jupiter in their orbits then the same force could keep the Earth’s moon going around it as the Earth moved around the Sun. His observations showed that those that believed the Earth orbits the Sun along with the other planets were right. The geocentrists, who believed that the Sun and all the planets orbited the Earth were wrong. On the basis of his scientific observations Galileo became a heliocentrist.
However the consequences of this paradigm shift was even further reaching not so much because of the change that occurred but why it occurred and who opposed it.
The Church opposed this scientific change not because it had a biblical position but because it defended an Aristotelian system of science that stated that the Earth was the centre of the universe. Galileo and others believed that science was a higher authority than the church. As a consequence the authority of the Bible was undermined.
Catastrophism to Gradualism
During the 17th and 18th centuries the dominant geological paradigm was catastrophism. The catastrophists, like Cuvier, believed that the geological features of the Earth were the result of many catastrophic events, one of which was the worldwide flood in the days of Noah.
However, by the end of the 18th century people were starting to propose new ideas. Hutton and Lyell were two leaders of this paradigm shift. They proposed that the geological features had not been formed quickly as the result of a series of catastrophes. Their new paradigm was one of gradual change. They argued that geological features were the result of processes that are occurring all the time. The gradual processes of erosion and deposition could if given enough time produce the many layers of sedimentary rock that the catastrophists said were formed quickly. The gradualists explained away the global flood of Noah that we read about in the Bible and other ancient writings.
Creation to Evolution
The 19th century was one in which peoples confidence in the Bible was undermined. The paradigm shift in geology meant many people believed the Earth was millions of years old. The way was open for a Darwinian explanation of biological origins. The theories of evolution that were popular during the early 19th century required a lot of time. The gradualist geologists gave evolutionary theorists the time they needed. Darwin provided the mechanism for the origin of species. Natural selection could if given enough time produce all the modern species of plant and animal. There was no need for God to create each kind of animal.
Faith in God to faith in science
These and many other paradigm shifts have marginalised and finally eliminated God. People today have faith in science. The technological achievements brought about by modern science have demonstrated its power to provide answers. Faith is under attack and the Bible is undermined. Even prominent figures in the church argue for evolutionary interpretations of the scriptures. We are ceaselessly bombarded with the "fact" that the universe, the world and all that is in it is the result of purposeless processes. The media and state education promote atheistic science which blinds people to the fact that God made everything. God no longer serves any purpose and the scientists of today have declared him to be dead.
Even so the Bible still speaks today and tells us that:
God’s invisible qualities - his eternal power and divine nature - have been clearly seen, being understood from what has been made.
There have been many paradigm shifts as humans tried to understand the universe, including:
- Geocentrism to Heliocentrism
- Catastrophism to Gradualism.
- Creation to Evolution
- Faith in God to faith in science
Geocentrism to Heliocentrism
In 1610 Galileo pointed his telescope at Jupiter and observed the orbits of four of its moons. He was convinced that if there was a force (which we now call gravity) that could keep the moons of Jupiter in their orbits then the same force could keep the Earth’s moon going around it as the Earth moved around the Sun. His observations showed that those that believed the Earth orbits the Sun along with the other planets were right. The geocentrists, who believed that the Sun and all the planets orbited the Earth were wrong. On the basis of his scientific observations Galileo became a heliocentrist.
However the consequences of this paradigm shift was even further reaching not so much because of the change that occurred but why it occurred and who opposed it.
The Church opposed this scientific change not because it had a biblical position but because it defended an Aristotelian system of science that stated that the Earth was the centre of the universe. Galileo and others believed that science was a higher authority than the church. As a consequence the authority of the Bible was undermined.
Catastrophism to Gradualism
During the 17th and 18th centuries the dominant geological paradigm was catastrophism. The catastrophists, like Cuvier, believed that the geological features of the Earth were the result of many catastrophic events, one of which was the worldwide flood in the days of Noah.
However, by the end of the 18th century people were starting to propose new ideas. Hutton and Lyell were two leaders of this paradigm shift. They proposed that the geological features had not been formed quickly as the result of a series of catastrophes. Their new paradigm was one of gradual change. They argued that geological features were the result of processes that are occurring all the time. The gradual processes of erosion and deposition could if given enough time produce the many layers of sedimentary rock that the catastrophists said were formed quickly. The gradualists explained away the global flood of Noah that we read about in the Bible and other ancient writings.
Creation to Evolution
The 19th century was one in which peoples confidence in the Bible was undermined. The paradigm shift in geology meant many people believed the Earth was millions of years old. The way was open for a Darwinian explanation of biological origins. The theories of evolution that were popular during the early 19th century required a lot of time. The gradualist geologists gave evolutionary theorists the time they needed. Darwin provided the mechanism for the origin of species. Natural selection could if given enough time produce all the modern species of plant and animal. There was no need for God to create each kind of animal.
Faith in God to faith in science
These and many other paradigm shifts have marginalised and finally eliminated God. People today have faith in science. The technological achievements brought about by modern science have demonstrated its power to provide answers. Faith is under attack and the Bible is undermined. Even prominent figures in the church argue for evolutionary interpretations of the scriptures. We are ceaselessly bombarded with the "fact" that the universe, the world and all that is in it is the result of purposeless processes. The media and state education promote atheistic science which blinds people to the fact that God made everything. God no longer serves any purpose and the scientists of today have declared him to be dead.
Even so the Bible still speaks today and tells us that:
God’s invisible qualities - his eternal power and divine nature - have been clearly seen, being understood from what has been made.
Did humans evolve from apes?
Introduction
Do the fossils of ape-like creatures that we find in our museums and see described in news stories and books on evolution prove that humans evolved from ape-like ancestors?
In this article we will look at some of the evidence to see just how strong it is, starting by a brief review of the more important fossils which are considered to be human ancestors:
• Genus Ardipithecus (possibly two or three species)
• Genus Australopithecus (at least three species)
• Genus Homo (at least 5 species and possibly as many as 9 species. This group includes modern humans (Homo sapiens). I will discuss only three of the fossil species; Homo habilis, Homo erectus and Homo floresiensis.
There is no general agreement among evolutionists on which species was the ancestor of modern humans, although it is suggested by some that one of the Australopithecus species was the last common ancestor. The current consensus appears to be that H. sapiens evolved from H. erectus and that H. erectus is descended from H. habilis.
The Fossils
Ardipithecus
These creatures were ape-like animals about the size of a modern chimpanzee. Work published in 2009 (White et al) shows that these creatures, with brains the size of chimpanzees, were able to move through the trees in an upright posture, using both hands and feet to grip branches.
Australopithecus
The best known Australopithecus species is A. afarensis for which there are a relatively large number of samples. This species is accepted by many researchers as the most likely candidate for a human ancestor. Possibly the best-known specimen of A. afarensis is AL 288-1 ("Lucy"), found in 1974 at Hadar, Ethiopia (Johanson and Taieb, 1976).
These creatures display an intriguing mix of characters. They appear to be designed to move in three different ways. The structure of the fingers and feet suggests that they were adept at climbing trees. They also had wrists and fingers which are consistent with knuckle-walking just like today’s great apes. The structure of the pelvis suggests that they would have been able to walk upright.
Laetoli footprints
The Laetoli footprints are very important because they were made by a creature which walked upright, supposedly over 3 million years ago. The footprints show that whoever made them had a human-like foot arch (Leakey and Hay, 1979) and one reconstructed A. afarensis foot has just such an arch.
However, Harcourt-Smith and Hilton claim that the reconstruction is actually based on a patchwork of bones from 3.2-million-year-old afarensis and 1.8-million-year-old H. habilis. Furthermore, one of the bones used to determine whether the foot was in fact arched (the navicular) is from H. habilis, not A. afarensis (Wong, 2007).
The researchers first compared the gaits of modern humans walking on sand with two sets of the fossil tracks. This analysis confirmed that the ancient footprints were left by individuals who had a striding bipedal gait very much like that of people today. The team also examined naviculars of A. afarensis, H. habilis, chimpanzees and gorillas. The dimensions of the H. habilis navicular fell within the modern
human range. In contrast, the A. afarensis bone resembled that of the flat-footed apes, making it improbable that its foot had an arch like our own. As such, the researchers report, A. afarensis almost certainly did not walk like us or, by extension, like the hominids at Laetoli.
Homo habilis
The most definitive statement one can make about H. habilis is that it is very difficult to define this species accurately. Indeed it has been said that the species is a mishmash of traits and specimens, whose composition depends upon which researcher one asks. Some specimens are very like the Australopithecines while others are very like H. erectus. Brain size varies from about 600 to 800 ml.
A foot attributed to this species is essentially human. Another specimen has hand bones that would have given it a human-like precision grip. A recent paper by Spoor et al (2007) provides information that helps to define H. habilis, but also suggests that H. habilis and H. erectus actually lived at the same time and it is very unlikely that H. erectus evolved from H. habilis.
Homo erectus
This species was first described in the late 1800s as Pithecanthropus erectus and has since been renamed Homo erectus. They had limbs of human proportions and a brain volume of about 900ml which is just outside the lower limit for modern humans. One of the most complete skeletons (KNMWT 15000) of this species was found in Kenya in 1984 (Brown et al, 1985). It was described as being
very similar to modern humans but with enough differences to justify the original designation as a separate species. However, recently described fossils have complicated the picture by suggesting that some specimens of H. erectus were more similar to H. habilis than previously thought and in some respects similar to australopiths (Lordkipanidze et al, 2007).
Homo floresiensis
H. floresiensis (which has been called the hobbit, because of its small size) was a small creature of about one metre in height with a brain volume of about 380ml (Brown et al, 2004). This species, if it is truly human, would indicate that genus Homo was much more varied in terms of shape and size and probably lifestyle than previously believed. However, it does not really constitute evidence for the evolution of humans from apes, as it was in existence at the same time as H. sapiens.
Analysis of the fossils
When carrying out evaluations of the fossils, scientists take into account many factors which include, but are not limited to, the measurement of the relative proportions of the limb bones, skull morphology, architecture of the hands, wrists and shoulders to determine whether or not the specimen is consistent with knuckle-walking and or brachiation (moving by swinging with the arms from one hold to another), examination of the legs and hips to determine whether or not the creature was a biped. Examination of the semi-circular canals also provides clues as to the normal orientation of the creatures. Anthropologists put all this information together when they try to determine the evolutionary history of
humans.
Humero-femoral index
One important characteristic is the ratio of the length of the arms and legs (usually expressed as the humero-femoral index). Apes have longer arms than legs, while humans have arms that are shorter than their legs, therefore the humero-femoral index of apes varies from about one to 1.3, while that for humans is about 0.7. Richmond et al (2002) have reported that the humero-femoral index for Ardipithecus and Australopithecus was about one.
Brain size
Ardipithecus and Australopithecus had a brain size of around 400ml, while H. habilis specimens generally have brain sizes of about 600 to 800ml. The brain size of H. erectus (about 900ml) is smaller than the average value for modern humans (which average about 1300ml). It is assumed that these findings show the evolution of the large human brain.
Knuckle-walking
Studies of the hands and wrists of Australopithecus afarensis and anamensis show that they “retain specialized wrist morphology associated with knuckle-walking” (Richmond and Strait, 2000).
The significance of this is unclear. Most seem to consider these features to be vestiges of a knucklewalking past. However, we would suggest that Australopithecus would have used both knucklewalking and bipedalism.
Brachiation
Apes have arms which are designed for brachiation. The structure of the arms and shoulders of Australopithecus is consistent with this mode of locomotion. Some specimens also have curved finger bones which are a feature of tree-climbing creatures.
Semi-circular canals
The semi-circular canals are organs of the inner ear which allow us to balance and orient ourselves in space. The orientation of the semi-circular canals reflects posture and balance. The plane of orientation of australopithecine inner ear canals revealed by CAT scans shows that they would have been able to move effectively by switching between bipedalism and arboreal climbing (Spoor et al, 1994). Furthermore, they concluded that only H. erectus could be considered an obligate biped, while a H. habilis specimen was not.
Discussion
There are a number of issues which should be mentioned in any discussion of human origins. Firstly, even the best fossils are fragmentary. Secondly, assigned dates conflict with “advanced features” and thirdly, there is a conflict of opinion among the experts.
Fragmentary fossils
Many of these fossils are fragmentary (even the well-known fossil “Lucy” is only 20% complete) and therefore interpretation is difficult and sometimes inconsistent. An example of the conflicting interpretation can be found in the papers by Richmond et al (2002) and Haeusler and McHenry (2004). The first concludes that H. habilis was more ape-like and the latter conclude that it had a body of essentially human proportions. There is continued disagreement about which specimens should be attributed to which species. This is a particularly acute problem for H. habilis but is also a problem for H. erectus. A review of the literature on H. habilis shows that different researchers attribute different specimens to habilis, and few can agree on what traits define habilis. It seems that habilis may not be a valid species at all, while
others have suggested that it should be called Australopithecus habilis.
Dating versus form
The dating of specimens also leads to difficulties. This is linked with the question of which specimens are ancestors of modern humans and which are “evolutionary dead-ends”. The Laetoli footprints are dated at 3.6 million years and were clearly made by a foot that is not distinguishable from the foot of a modern human who habitually goes barefoot. A very modern looking maxilla (AL 666-1) has been
assigned an age of 2.3 million years. Yet we are told that the earliest H. sapiens is no more than a few 100 000 years old. The recently published evidence suggests that H. habilis and H. erectus lived at the same time (Spoor, 2007). Therefore, the idea that H. erectus arose from H. habilis is in considerable doubt.
Conflicting expert opinion
It should also be noted that the different fossil experts, in their different interpretations of the evidence, have between themselves probably ruled out all the fossils as human ancestors. This suggests that a case could be made that none of them are fossil ancestors of humans.
This brief review shows that the currently available evidence is not sufficient to allow anyone to claim that they know how we evolved from apes. Indeed as more fossils are discovered it appears that the story becomes more complicated. The large variety of different species and the fragmentary nature of much of the evidence provide plenty of opportunity for various speculative pathways to humans.
Indeed, it is difficult to make definite statements about how hominid evolution has occurred. Furthermore, the latest research on Ardipithicus makes a coherent evolutionary account of human origins even more difficult, as it is not consistent with previous assumptions about human origins (White et al, 2009).
Evidence versus assumptions
Evolutionists agree that there was an increase in brain size, a change from knuckle-walking and treeclimbing to obligate bipedalism and an increase in manual dexterity. However, the details remain unclear and there is no general agreement on what caused these changes and the exact sequence of events. Arguably, rather than being a conclusion springing from the fossil evidence, some scientists are
looking for evidence to show a series of changes involving a transition to bipedalism, increasing brain size and an increase in manual dexterity, because that seems the most logical way in which we might expect an evolutionary pathway to occur. The proposed sequence of changes is, therefore, based on assumptions that provide a framework within which the evidence is interpreted.
Possible alternative explanations of the fossils
The australopithicine specimens are clearly from a group of animals which could move on the ground both equally well on two legs or by knuckle-walking (like gorillas and chimpanzees), while also being capable of moving through trees by brachiation. Bonobo apes are modern creatures which are probably very close to australopithicines in terms of locomotory repertoire and they spend a good deal of time
walking upright, suggesting that australopiths are no more than extinct apes.
One of the contested links between humans and apes is H. habilis, which, as we have seen, is a mixture of various different fossil specimens that probably do not belong together. It is fair to say that some of the H. habilis fossils could be assigned to genus Homo and others to the Australopithecus. However, while this is not necessarily fatal to the evolutionary story, it does show that the evidence is not conclusive and is open to many different interpretations.
Evolutionists emphasise the small brain size of H. habilis and H. erectus as evidence for evolution and this is perhaps their strongest argument. However, the absolute minimum for human brain volume is not known with any certainty. Indeed it is agreed that architecture is more important than volume. The minimum for a normal modern human is about 1000ml and H. erectus with a brain volume of around
900ml is very close. There is no good reason to assume that H. erectus was less intelligent than modern humans, therefore, it seems that it could have been human.
Evolutionists claim that the fact that it is difficult to determine whether some fossils are human or ape shows that they are transitional. It seems likely that the problem arises because of the fragmentary nature of the evidence. Evolutionists predict that as more fossils come to light the transition will become clearer. However, we predict that, as evidence accumulates, it will become clear that fossil apes were ancestors of modern apes and fossil humans were ancestors of modern humans.
A good case could be made for considering some H. erectus specimens, with brain sizes around 900ml to be fully human, consistent with the great morphological variety present within the species H. sapiens. Indeed it should be noted that humans today show a wide variation in morphology, from the various tribes of African pygmies, to Europeans, to the Maasai and to the Inuit.
Conclusion
As we have seen, there are many difficulties with the evolutionary account of human origins. The fragmentary evidence results in differing opinions on whether a fossil is a human ancestor or a creature which left no descendents. Indeed, as has been pointed out by Lieberman (2007) the picture has recently become more complicated with the discovery of new fossils from Georgia. It seems that there
is a need for much more conclusive evidence before anyone can claim to have proved that we evolved from an ape-like ancestor. However, we believe that as more fossils are analysed it will become clearer that humans could not have evolved from ape-like ancestors.
© Marc Surtees 2011
References
Brown, F., J. Harris, R. Leakey, and A. Walker. Early Homo erectus skeleton from west Lake
Turkana, Kenya.
Nature 316:788-92 (1985)
Brown, P., Sutikna, T., Morwood, M. J., Soejono, R. P., Jatmiko, Saptomo, E.W. and Due, R.A. A
new small-bodied hominin from the Late Pleistocene of Flores, Indonesia.
Nature 431, 1055-1061 (2004)
Haeusler, M. and McHenry, H.M. Body proportions of Homo habilis reviewed.
Journal of Human Evolution 46 433–465 (2004)
Johanson, D. C. and Taieb, M. Plio—Pleistocene hominid discoveries in Hadar, Ethiopia.
Nature 260, 293 – 297 (1976)
Leakey, M. D. and Hay, R. L. Pliocene footprints in the Laetoli Beds at Laetolil, northern Tanzania.
Nature 278:317-23 (1979).
Lieberman, D.E., Palaeoanthropology: Homing in on early Homo, Nature, 449, 291 - 292 (2007)
Lordkipanidze, D et al. Postcranial evidence from early Homo from Dmanisi, Georgia.
Nature, 449, 305-310 (2007)
Richmond, B.G. & Strait, D.S. Evidence that humans evolved from a knuckle-walking ancestor.
Nature 404, 382-384 (2000)
Richmond, B.G., Aiello, L.C. and Wood, B.A. Early hominin limb proportions.
Journal of Human Evolution 43, 529–548 (2002)
Spoor, F., Leakey, M. G., Gathogo, P. N., Brown, F. H., Antón, S. C., McDougall, I., Kiarie, C.,
Manthi, F. K. & Leakey, L. N. Implications of new early Homo fossils from Ileret, east of Lake
Turkana, Kenya. Nature 448, 688-691 (2007)
Spoor F., Wood B. and Zonneveld, F. Implications of early hominid labyrinthine morphology for
evolution of human bipedal locomotion. Nature 369, 645 – 648 (1994)
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http://www.sciam.com/article.cfm?articleID=0005C9B3-03AE-12D8-BDFD83414B7F0000
Downloaded 1st Jan 2007
Introduction
Do the fossils of ape-like creatures that we find in our museums and see described in news stories and books on evolution prove that humans evolved from ape-like ancestors?
In this article we will look at some of the evidence to see just how strong it is, starting by a brief review of the more important fossils which are considered to be human ancestors:
• Genus Ardipithecus (possibly two or three species)
• Genus Australopithecus (at least three species)
• Genus Homo (at least 5 species and possibly as many as 9 species. This group includes modern humans (Homo sapiens). I will discuss only three of the fossil species; Homo habilis, Homo erectus and Homo floresiensis.
There is no general agreement among evolutionists on which species was the ancestor of modern humans, although it is suggested by some that one of the Australopithecus species was the last common ancestor. The current consensus appears to be that H. sapiens evolved from H. erectus and that H. erectus is descended from H. habilis.
The Fossils
Ardipithecus
These creatures were ape-like animals about the size of a modern chimpanzee. Work published in 2009 (White et al) shows that these creatures, with brains the size of chimpanzees, were able to move through the trees in an upright posture, using both hands and feet to grip branches.
Australopithecus
The best known Australopithecus species is A. afarensis for which there are a relatively large number of samples. This species is accepted by many researchers as the most likely candidate for a human ancestor. Possibly the best-known specimen of A. afarensis is AL 288-1 ("Lucy"), found in 1974 at Hadar, Ethiopia (Johanson and Taieb, 1976).
These creatures display an intriguing mix of characters. They appear to be designed to move in three different ways. The structure of the fingers and feet suggests that they were adept at climbing trees. They also had wrists and fingers which are consistent with knuckle-walking just like today’s great apes. The structure of the pelvis suggests that they would have been able to walk upright.
Laetoli footprints
The Laetoli footprints are very important because they were made by a creature which walked upright, supposedly over 3 million years ago. The footprints show that whoever made them had a human-like foot arch (Leakey and Hay, 1979) and one reconstructed A. afarensis foot has just such an arch.
However, Harcourt-Smith and Hilton claim that the reconstruction is actually based on a patchwork of bones from 3.2-million-year-old afarensis and 1.8-million-year-old H. habilis. Furthermore, one of the bones used to determine whether the foot was in fact arched (the navicular) is from H. habilis, not A. afarensis (Wong, 2007).
The researchers first compared the gaits of modern humans walking on sand with two sets of the fossil tracks. This analysis confirmed that the ancient footprints were left by individuals who had a striding bipedal gait very much like that of people today. The team also examined naviculars of A. afarensis, H. habilis, chimpanzees and gorillas. The dimensions of the H. habilis navicular fell within the modern
human range. In contrast, the A. afarensis bone resembled that of the flat-footed apes, making it improbable that its foot had an arch like our own. As such, the researchers report, A. afarensis almost certainly did not walk like us or, by extension, like the hominids at Laetoli.
Homo habilis
The most definitive statement one can make about H. habilis is that it is very difficult to define this species accurately. Indeed it has been said that the species is a mishmash of traits and specimens, whose composition depends upon which researcher one asks. Some specimens are very like the Australopithecines while others are very like H. erectus. Brain size varies from about 600 to 800 ml.
A foot attributed to this species is essentially human. Another specimen has hand bones that would have given it a human-like precision grip. A recent paper by Spoor et al (2007) provides information that helps to define H. habilis, but also suggests that H. habilis and H. erectus actually lived at the same time and it is very unlikely that H. erectus evolved from H. habilis.
Homo erectus
This species was first described in the late 1800s as Pithecanthropus erectus and has since been renamed Homo erectus. They had limbs of human proportions and a brain volume of about 900ml which is just outside the lower limit for modern humans. One of the most complete skeletons (KNMWT 15000) of this species was found in Kenya in 1984 (Brown et al, 1985). It was described as being
very similar to modern humans but with enough differences to justify the original designation as a separate species. However, recently described fossils have complicated the picture by suggesting that some specimens of H. erectus were more similar to H. habilis than previously thought and in some respects similar to australopiths (Lordkipanidze et al, 2007).
Homo floresiensis
H. floresiensis (which has been called the hobbit, because of its small size) was a small creature of about one metre in height with a brain volume of about 380ml (Brown et al, 2004). This species, if it is truly human, would indicate that genus Homo was much more varied in terms of shape and size and probably lifestyle than previously believed. However, it does not really constitute evidence for the evolution of humans from apes, as it was in existence at the same time as H. sapiens.
Analysis of the fossils
When carrying out evaluations of the fossils, scientists take into account many factors which include, but are not limited to, the measurement of the relative proportions of the limb bones, skull morphology, architecture of the hands, wrists and shoulders to determine whether or not the specimen is consistent with knuckle-walking and or brachiation (moving by swinging with the arms from one hold to another), examination of the legs and hips to determine whether or not the creature was a biped. Examination of the semi-circular canals also provides clues as to the normal orientation of the creatures. Anthropologists put all this information together when they try to determine the evolutionary history of
humans.
Humero-femoral index
One important characteristic is the ratio of the length of the arms and legs (usually expressed as the humero-femoral index). Apes have longer arms than legs, while humans have arms that are shorter than their legs, therefore the humero-femoral index of apes varies from about one to 1.3, while that for humans is about 0.7. Richmond et al (2002) have reported that the humero-femoral index for Ardipithecus and Australopithecus was about one.
Brain size
Ardipithecus and Australopithecus had a brain size of around 400ml, while H. habilis specimens generally have brain sizes of about 600 to 800ml. The brain size of H. erectus (about 900ml) is smaller than the average value for modern humans (which average about 1300ml). It is assumed that these findings show the evolution of the large human brain.
Knuckle-walking
Studies of the hands and wrists of Australopithecus afarensis and anamensis show that they “retain specialized wrist morphology associated with knuckle-walking” (Richmond and Strait, 2000).
The significance of this is unclear. Most seem to consider these features to be vestiges of a knucklewalking past. However, we would suggest that Australopithecus would have used both knucklewalking and bipedalism.
Brachiation
Apes have arms which are designed for brachiation. The structure of the arms and shoulders of Australopithecus is consistent with this mode of locomotion. Some specimens also have curved finger bones which are a feature of tree-climbing creatures.
Semi-circular canals
The semi-circular canals are organs of the inner ear which allow us to balance and orient ourselves in space. The orientation of the semi-circular canals reflects posture and balance. The plane of orientation of australopithecine inner ear canals revealed by CAT scans shows that they would have been able to move effectively by switching between bipedalism and arboreal climbing (Spoor et al, 1994). Furthermore, they concluded that only H. erectus could be considered an obligate biped, while a H. habilis specimen was not.
Discussion
There are a number of issues which should be mentioned in any discussion of human origins. Firstly, even the best fossils are fragmentary. Secondly, assigned dates conflict with “advanced features” and thirdly, there is a conflict of opinion among the experts.
Fragmentary fossils
Many of these fossils are fragmentary (even the well-known fossil “Lucy” is only 20% complete) and therefore interpretation is difficult and sometimes inconsistent. An example of the conflicting interpretation can be found in the papers by Richmond et al (2002) and Haeusler and McHenry (2004). The first concludes that H. habilis was more ape-like and the latter conclude that it had a body of essentially human proportions. There is continued disagreement about which specimens should be attributed to which species. This is a particularly acute problem for H. habilis but is also a problem for H. erectus. A review of the literature on H. habilis shows that different researchers attribute different specimens to habilis, and few can agree on what traits define habilis. It seems that habilis may not be a valid species at all, while
others have suggested that it should be called Australopithecus habilis.
Dating versus form
The dating of specimens also leads to difficulties. This is linked with the question of which specimens are ancestors of modern humans and which are “evolutionary dead-ends”. The Laetoli footprints are dated at 3.6 million years and were clearly made by a foot that is not distinguishable from the foot of a modern human who habitually goes barefoot. A very modern looking maxilla (AL 666-1) has been
assigned an age of 2.3 million years. Yet we are told that the earliest H. sapiens is no more than a few 100 000 years old. The recently published evidence suggests that H. habilis and H. erectus lived at the same time (Spoor, 2007). Therefore, the idea that H. erectus arose from H. habilis is in considerable doubt.
Conflicting expert opinion
It should also be noted that the different fossil experts, in their different interpretations of the evidence, have between themselves probably ruled out all the fossils as human ancestors. This suggests that a case could be made that none of them are fossil ancestors of humans.
This brief review shows that the currently available evidence is not sufficient to allow anyone to claim that they know how we evolved from apes. Indeed as more fossils are discovered it appears that the story becomes more complicated. The large variety of different species and the fragmentary nature of much of the evidence provide plenty of opportunity for various speculative pathways to humans.
Indeed, it is difficult to make definite statements about how hominid evolution has occurred. Furthermore, the latest research on Ardipithicus makes a coherent evolutionary account of human origins even more difficult, as it is not consistent with previous assumptions about human origins (White et al, 2009).
Evidence versus assumptions
Evolutionists agree that there was an increase in brain size, a change from knuckle-walking and treeclimbing to obligate bipedalism and an increase in manual dexterity. However, the details remain unclear and there is no general agreement on what caused these changes and the exact sequence of events. Arguably, rather than being a conclusion springing from the fossil evidence, some scientists are
looking for evidence to show a series of changes involving a transition to bipedalism, increasing brain size and an increase in manual dexterity, because that seems the most logical way in which we might expect an evolutionary pathway to occur. The proposed sequence of changes is, therefore, based on assumptions that provide a framework within which the evidence is interpreted.
Possible alternative explanations of the fossils
The australopithicine specimens are clearly from a group of animals which could move on the ground both equally well on two legs or by knuckle-walking (like gorillas and chimpanzees), while also being capable of moving through trees by brachiation. Bonobo apes are modern creatures which are probably very close to australopithicines in terms of locomotory repertoire and they spend a good deal of time
walking upright, suggesting that australopiths are no more than extinct apes.
One of the contested links between humans and apes is H. habilis, which, as we have seen, is a mixture of various different fossil specimens that probably do not belong together. It is fair to say that some of the H. habilis fossils could be assigned to genus Homo and others to the Australopithecus. However, while this is not necessarily fatal to the evolutionary story, it does show that the evidence is not conclusive and is open to many different interpretations.
Evolutionists emphasise the small brain size of H. habilis and H. erectus as evidence for evolution and this is perhaps their strongest argument. However, the absolute minimum for human brain volume is not known with any certainty. Indeed it is agreed that architecture is more important than volume. The minimum for a normal modern human is about 1000ml and H. erectus with a brain volume of around
900ml is very close. There is no good reason to assume that H. erectus was less intelligent than modern humans, therefore, it seems that it could have been human.
Evolutionists claim that the fact that it is difficult to determine whether some fossils are human or ape shows that they are transitional. It seems likely that the problem arises because of the fragmentary nature of the evidence. Evolutionists predict that as more fossils come to light the transition will become clearer. However, we predict that, as evidence accumulates, it will become clear that fossil apes were ancestors of modern apes and fossil humans were ancestors of modern humans.
A good case could be made for considering some H. erectus specimens, with brain sizes around 900ml to be fully human, consistent with the great morphological variety present within the species H. sapiens. Indeed it should be noted that humans today show a wide variation in morphology, from the various tribes of African pygmies, to Europeans, to the Maasai and to the Inuit.
Conclusion
As we have seen, there are many difficulties with the evolutionary account of human origins. The fragmentary evidence results in differing opinions on whether a fossil is a human ancestor or a creature which left no descendents. Indeed, as has been pointed out by Lieberman (2007) the picture has recently become more complicated with the discovery of new fossils from Georgia. It seems that there
is a need for much more conclusive evidence before anyone can claim to have proved that we evolved from an ape-like ancestor. However, we believe that as more fossils are analysed it will become clearer that humans could not have evolved from ape-like ancestors.
© Marc Surtees 2011
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