Ambling Along With 4.5 Million Year Old Flat Feet

A hominid species predating Lucy, (Australopithecus africanus) has been more fully described. Journalists have had first crack at the issue of Science in which the updated description of the species,  Ardipithecus ramidus (from 4.5 million years ago), appears. The rest of us could only see this issue late in the day.  The recently studied Ardipithecus specimens include the feet, which were clearly missing on Lucy (from 3.2 million years ago), but present among a limited set of other Australopithecus specimens. Ardipithecus was originally discovered in 1994 in Ethiopia.

The treasure trove of the day are the eleven fresh papers detailing  Ardipithecus and it’s (with a delay in publication for years) environment including botanical and other specimens found locally, the anatomy, and evolutionary conjectures all published in Science magazine. Details on excavation, locale, personnel, CT scans, three-dimensional reconstruction, dimensions and sizes of the specimens, were included in this comprehensive set of articles.

Ardipithecus was thought to live and spend time in trees, but would carefully climb rather than swing from the branches. Ardipithecus was also believed to spend time foraging for food, primarily plant based, on the ground while moving in a bipedal manner. Australopithecus was not a runner, nor is it likely with feet less well adapted  was Ardipithecus. Among other lower extremity differences between Homo erectus and Ardipithecus were flatter feet and an opposable big toe (metatarsus primus varus – actually  metatarsus primus adductus – a large angle in stance between the first and second metatarsal bones – but I’ll have to check out more photos and study the  articles in detail in Science magazine). If Ardipithecus twiddled her thumbs she could likely also twiddle her opposable big toes. Speaking of toes, one of the changes that is thought to make running possible for the later hominids was a shortening of the length of toes, in addition to an increase in arch height, and a host of other biomechanical changes.

An opposable big toe with a non-functional first ray makes for a decidedly different bipedal gait than even Lucy had. The tight grouping of the cuneiforms present in later hominids allowed the first ray to function effectively in weight transfer and propulsion rather than the little it could do as an opposable digit without stability in ground based bipedal gait. Of course a humanoid great toe does not offer much assistance in the trees. An important feature to note is that Ardipithecus did not knuckle walk, as can be determined from the wrist and hand structure, during bipedal gait, although the upper extremities were long. Nor did Ardipithecus appear to brachiate or swing through the tree branches.

Below are images of the upcoming cover of Science magazine with Ardipithecus on the cover and an image of Lucy missing her feet.

Update: Freely available articles at Science

Ardipithecus

Lucy on The Ground with no Toes

Related Articles

Movement and Exercise Spurred Evolutionary Brain Development

In The Beginning: We Were Made To Stand Upright

Walk This Way (Early Foot Prints  of Homo erectus)

Additional References:

Bonus Music: Ventures – “Walk Don’t Run” – Primitive filming (B&W)

Recent Evolution of Walk Don’t Run

Stimulating Brain Development: Evolution Of The Brain Spurred By Movement (a speculative hypothesis)

We previously mentioned the early hominid development of upright, obligatory, habitual bipedal posture mentioning the richer protein and calorie dense food which may have enabled better brain development. We’ll expand on that a bit with a “big think” and take it down a slightly different road. And we can have a bit of fun with a speculative hypothesis.

My thought (and hypothesis) is that exercise, viewed as aerobic movement, was the spur to development of a larger brain as is found in later hominids and modern humans. Tool making, enhanced socialization, all other more modern features and the larger cortex itself derive from motion, movement, and the positive effect that “exercise” has on the chemistry of the brain.

As we stop and think about what made the brain enlarge we hear those who say that bipedal movement freed up our hands. Now you can walk and juggle or do other tricks.  Another theory posits that early hominids could now carry food back to their tribe, make tools, ultimately jewelry and developed other useful talents. Whatever occurred likely was multi-factorial and not a simple single means event.

In keeping with Darwinian principles, it is incorrect to say that the environment created changes. We need to look to see what environmental features were taken advantage of by those best prepared to do so. Mutations are random, selection is purposeful, and geared towards the survival of those most fit for the environment. There are a variety of phenotypes present at any time, and those exhibiting desirable and helpful characteristics do survive and pass on those useful genes.

Mammalian brains produce BDNF (brain derived neurotrophic factor) which assists in neural plasticity and in the creation of new neural cross links. Humans today moving at high rates of oxygen uptake show that at up to 60% of maximum VO2, several things come into play. The first is an increase in Cerebral Blood Flow (CBF). The CBF increases as does the production of  BDNF and other compounds that among other effects stimulate brain growth and development. These other compounds include IGF-1 (insulin growth factor 1), VEGF (vascular endothelial growth factor), and FGF (fibroblast growth factor).

Bathing the brain in this enhanced biochemical “miracle grow” mix, likely would have resulted in superior neural growth and response for those who were best able to respond to this physical and neurological environment.  This seems to have been a contributing factor in the maximal development of the early hominid brain, and continued down through the hominid line.

Those most able to respond to the biochemical results of their activity of  motion, movement, and gathering would have become the smartest of the lot and been most likely to survive . They would be better suited for survival and more able to pass on their genes.  Bipedal movement in hominids was first to be short in duration. Lasting for only a limited distance and allowed for limited scavenging.  Ultimately it resulted in habitual and obligate bipedalism of longer duration, and finally in walking and then, later, running.

There have been debates over the energetics of bipedal motion versus brachiation and advantages over older forms of quadripedal locomotion. But with the thought that nothing gets wasted, if the energetics don’t balance perfectly it is probable that the energy itself that may not have been optimally efficient for walking, certainly was put to excellent use in the development, enhancement, and gradual evolution of the hominid and ultimately modern human brain.

Bipedal walking allowed the former tree apes a  better and more easily sustained motion. This  over the course of time, possibly led to persistence hunting, or at the least an expanded range for gathering, foraging, and then much later hunting. And the migration out of Africa was another sustained effort and may have stimulated brain development.

Sensory stimuli, socialization, diet, and many factors went into brain evolution and development. Then, as now, it is likely that the sustained efforts of moving increased focus, attention, and concentration. Creating mental maps of where they had been, and how to return home gave their small brains a work out. And speculating a bit, ultimately mental maps led to many other things and perhaps even primitive games of hide and seek.  Later came blind folded chess and google maps.

Many facets of evolutionary thought are interesting and valuable. Socialization and network theory, the role of sensory stimulation all are explorable, viable theories and played a major role in evolution. Here we’ve brought into play another facet of hominid evolution not previously described. The energetics and resultant neurochemical (and other changes) as a result of  motion, movement and exercise is a contributing and driving force for brain development and evolution. Put this in the context of the fact that everything moves and there is nothing entirely still in the universe, we have another small factor to consider about our world and how we and it have evolved.

So it seems we weren’t just born to walk or run. We were born to think, develop and evolve. In fact, we’ve evolved to evolve. And evolution continues today. If your thoughts stop with barefoot running, and you think our evolution stopped then, you’ve got a lot more thinking and catching up to do. Exercise and movement are good for what ails you, and assisted in the development of today’s modern human brain.

(Outline presented at American Podiatric Medical Association Annual Scientific Seminar. August 1, 2009. Toronto, Canada)

Many people have played the facebook game “What’s Your Real Age”. My guess that those who played it wanted to feel they were younger than their biological age. Telomere length seems to be the real way to determine actual “biological age”. These are the real “biological clocks”. Telomeres are repetitive sequences at the ends of chromosomes that shorten with age and also shorten in certain metabolic and disease states. They are sometimes called the protective “caps” on the ends of chromosomes. Because of the manner in which chromosomes are replicated during cellular division, a bit of the telomere is not copied with each subsequent cellular generation resulting in a gradual shortening of the telomere restriction fragment (TRF) length.

Telomeres Shorten With Age

A recent study showed that people who perform more leisure time physical activity have longer telomeres. Another recent study, with an admitted low subject number, demonstrated that eating processed meat  such as sliced bologna would also slice down the size of your telomeres. This study, published in the American Journal of Clinical Nutrition did not find other expected dietary associations.

The Cardiovascular Health Study (2007) found inverse correlations (shortened telomeres) between TRF length and fasting glucose level, fasting insulin level, systolic and diastolic blood pressure, carotid intima-media thickness, interleukin-6, high BMI, overweight (in men).

Some studies including one with “voluntary running” in mice showed the production of telomere protective compounds with the “voluntary” running. On a side note,  I’ll have to look closer at this study. If we can can get mice to  voluntarily participate in a “fitness” program, maybe we can figure out the secret to get more people to do so. Perhaps cheese is the answer.

Aubert and Lansdorp (2008) published an excellent review of  the biology of telomeres and aging. They noted that Barbara McClintock, in her 1983 Nobel acceptance speech pointed out the significance of cellular response to stress and dangers. “In the future attention undoubtedly will be centered on the genome, and with greater appreciation of its significance as a highly sensitive organ of the cell, monitoring genomic activities and correcting common errors, sensing the unusual and unexpected events, and responding to them, often by restructuring the genome. We know about the components of genomes that could be made available for such restructuring. We know nothing, however, about how the cell senses danger and instigates responses to it that often are truly remarkable.”

Short Telomeres Trigger Cellular Defences

The shortened telomeres are likely sending more “damage” signals to the cells which lead to a number of biochemical pathways which degrade the contents of the cell. Studies on cellular senescence, apoptosis, and research on genomics is leading us to a better understanding, but we have a long ways to go. The complexity never ends, but it continues to unwind. And you can almost hear the tick tock of the biological clock. Your best means of slowing up the ticking are life habit changes: exercise regularly, maintain healthy body weight, don’t smoke and eat a healthy diet.
What’s my age again? – Blink 182

What's My Age Again?

References:

Lynn F. Cherkas, PhD; Janice L. Hunkin, BSc; Bernet S. Kato, PhD; J. Brent Richards, MD; Jeffrey P. Gardner, PhD; Gabriela L. Surdulescu, MSc; Masayuki Kimura, MD, PhD; Xiaobin Lu, MD; Tim D. Spector, MD, FRCP; Abraham Aviv, MD. Arch Intern Med. 2008;168(2):154-158.

Annette L. Fitzpatrick1, Richard A. Kronmal2, Jeffrey P. Gardner3, Bruce M. Psaty1,4, Nancy S. Jenny5, Russell P. Tracy5,6, Jeremy Walston7, Masyuki Kimura3 and Abraham Aviv . Leukocyte Telomere Length and Cardiovascular Disease in the Cardiovascular Health Study. American Journal of Epidemiology 2007 165(1):14-21; doi:10.1093/aje/kwj346.

J. A Nettleton, A. Diez-Roux, N. S Jenny, A. L Fitzpatrick, and D. R Jacobs Jr. Dietary patterns, food groups, and telomere length in the Multi-Ethnic Study of Atherosclerosis (MESA). Am. J. Clinical Nutrition, November 1, 2008; 88(5): 1405 – 1412

Liza S.M. Wong, Hisko Oeseburg, Rudolf A. de Boer, Wiek H. van Gilst, Dirk J. van Veldhuisen and Pim van der Harst.. Telomere biology in cardiovascular disease: the TERC–/– mouse as a model for heart failure and ageing. Cardiovascular Research 2009 81(2):244-252; doi:10.1093/cvr/cvn337

Aubert, G. and P. M. Lansdorp (2008). “Telomeres and Aging.” Physiol. Rev. 88(2): 557-579.

The Bare Outline of Bipedal Beginnings

Humans are the only primate habitual, obligate, bipedal on the planet. And not only can we walk, but we can launch ourselves completely off the ground and run. It is important to note that running is a one legged exercise. Only one limb is in contact with the ground at any time. This has implications for both energetics, efficiency, and the type of injuries that we end up with in the present.

How did we get here? The middle part of the story is that there seems to be a relationship between tree apes and those of us who ended up on the ground. Our structure is homologous, yet different in many respects. In becoming the first runners the fossil and bone evidence seems to be that we first stood upright before our skull and brain enlarged. Australopithecus has a small skull, yet seems built for bipedal movement.  Some feel that Australopithecus could not run, and that it’s bipedal locomotion was a shuffling gait. Remnants of the apes remained, particularly the long upper limbs and curved fingers. Changes occurred in the feet. The great (first) toe and first metatarsal moved closer to the rest of the toes and was no longer opposable like the thumb. The limbs functioned better nearly straight. The pelvis changed and the spine changed to allow for limb connections. The knees could extend fully and lock.  The spine changed both with curves to better position the center of gravity and to allow for the new way in which the skull was oriented to allow for an upright head with eyes looking forward.

Following the development of upright posture, we had two free hands that could be used to carry tools, hunting implements, or food. We could move about fairly efficiently on the ground. We could range far in order to find food. Chimps and apes do not have a wide hunting range to gather food. As we ranged about, we found non-plant sources of protein. This enhanced the development of those built to use the protein, and allowed for eventually the development of a larger brain. This in turn led to the development of the genus homo, including Homo Erectus and later Homo Habilis.

The control of fire, and the use of fire for cooking made for easy to digest protein sources and richer, more calorie dense food. Some feel that the socialization that may have arisen around the ritual of cooking and meals helped enriched humans both culturally and socially. No food fights or no food!

As we developed more and more complex, those with larger brains, and skulls to hold them needed to be born through a larger pelvis. Eventually the pelvis enlarged in two different ways, Neandertal in width and our branch of hominids in an anterior – posterior direction.

Shortly we’ll take a look at the first runners. These first runners had larger gluteal muscles, a longer Achilles tendon, and even developed a bit of an arch along with toes that were all in line. Our knees could lock out. We already could look straight ahead and move on two limbs. As we became obligate bipeds we could no longer climb trees as well as those that came earlier.  I expect to have more details with recommended readings and references on my main web site. And of course, follow up here. To quote Charles Darwin in The Origin of Species: “To treat this subject at all properly, a long catalogue of dry facts should be given; but these I shall reserve for my future work.”

Science Magazine 323 Feb 27, 2009

Science magazine has just published an article on the oldest footprints found which correspond to modern day human biomechanical function. These footprints are about 1.5 Million years old and appear to belong to homo erectus, a species which predated homo sapiens.

The great toe was in similar alignment to modern day humans. An arch was present. Heel strike occurred at initial contact, weight transfer progressed forward with apparent foot function in the midfoot (midtarsal joint) proceeding in a modern manner. Weight bearing then went to the central metatarsals, (seemingly bearing more than the first metatarsal) followed by push off at the big toe.

The foot prints appear to show someone slowed to a near stop (or starting from a stop) and then picking up speed. To my eye, with an initial angle of gait being first high on the left, than on the right (about 24-26 degrees), followed by a narrow angle of gait (about 1 degree) as speed picked up, it looked as though the pre-human hominid was looking to the left, and then to the right. He likely would have been able to cross some of our streets, at least those with traffic bearing to the right side of the road. And in fact he may have avoided getting run over by a bovine, which blotted out part of one of his foot prints.

Bipedalism, walking on two limbs, was an important evolutionary step. Bipedalism is thought to have been present for about 6 million years.  It is energy efficient. It allows free hands to carry things, make tools, build things that are more complex than bird’s nests and beaver’s dams. It frees the hands  for hunting and fishing. Ultimately, it led to holding hands while walking. It led to artistic undertaking such as cave paintings, fashioning musical instruments, fingering the holes of a flute or playing chords and notes on strings. But, it also led some to throw stones at others. But that is another story.

The energy saved may have led to enhanced brain function. The energetics of bipedal walking, determined on an individual basis (some calculations have been done on chimpanzees) show a significant reduction in energy cost for walking in a bipedal manner. Some theorists believe that upright walking, and even running came before the larger skull and brain size.  That may very well have been true, based on these and other findings. There are many interesting adaptations and changes that occurred over the years. Some of the differences that occurred evolutionarily that are important to human bipedalism and are of significant, walking and running energetics include altered f0rm and function of the calf muscle, Achilles tendon, and the gluteal muscles. But, we can’t judge all of that from the footprints alone.

Science 323, 1197 (2009);  Early Hominin Foot Morphology Based on 1.5-Million-Year-Old Footprints from Ileret, Kenya. Matthew R. Bennett, et. al.

Science Now “Early Humans Toed The Line”

Music + Video: “Walk This Way”

Music + Video: “Walk The Line”