Refuting Creationism - How the 'Lizard' Part of Your Brain Influences Your Thinking

In a new Northwestern Medicine study, scientists sought to better understand how humans evolved to become so skilled at thinking about what’s happening in other peoples’ minds.

Amygdala is the organ in the limbic system (inner mind) —though a tiny little one is significantly responsible for our emotions which falls in the bracket of implicit memories.

Overthinking what you said? It’s your ‘lizard brain’ talking to newer, advanced parts of your brain: For Journalists - Northwestern University

Few things upset creationists more than evidence that they are not only apes and share a common ancestor with the other African apes, but that they also share a common ancestor even with non-mammals such as reptiles, and yet, as the American evolutionary biologist, Theodosius Dobzhansky reminds us, nothing in biology makes sense without the Theory of Evolution (TOE).

And one thing that does make sense is how the human brain is the result of an evolutionary process with ancestry in those common ancestors, including lizards.

A second thing that creationists who have deluded themselves into believing that mainstream biomedical scientists are giving up on the TOE and adopting the childish notion of intelligent design, will find distressing, is the news that the team who did this piece of research are firmly convinced that the structure of our brain and the way it works is the result of evolution, not magic.

The third thing is how this explains empathy, of which creationists often feign ignorance, claiming they get their sense of right and wrong from their invisible friend and have a handbook to tell them how to behave. The curious belief that even influenced supposed Christian intellectual 'giants' such as the smugly self-satisfied, C.S. Lewis, is despite the fact that one of the Golden Rules of human society, that even the founder of Christianity, Jesus, allegedly told his followers to apply - "Do unto others what you would they do unto you" or words to that effect, depend entirely on having the empathetic ability to know what someone else would want.

The research explains how this ability in humans comes from an ancestral ability to read social signals and form relationships, including an understanding of social hierarchies, possessed even by lizards.

Refuting Creationism - Teenage Puberty, 15,000 Years Before 'Creation Week'

Human life in the European Pleistocene

AI generated (ChatGPT4.0)

Reconstruction of Romito 2, a 16-year-old teenager with a form of dwarfism who lived 11,000 years ago in southern Italy.

Drawing by: Olivier Graveleau.

Realities of Ice Age puberty - University of Victoria

The thing about this study from a creationist perspective is its two-fold refutation of basic creationist dogma.

Firstly, it is not so much that teenagers in the last Ice Age went through puberty at pretty much the same age as modern teenagers, despite an assumed improvement in the diet of modern people compared to that of a Pleistocene hunter-gatherer, but that there were actually human teenagers 15,000 years before creationist dogma says that there was an Earth.

Secondly, there is the fact that the remains of these teenagers are available for analysis, when the mythical global genocidal flood, so beloved of creationists, should have swept it all away.

But counter-factual creationism is never perturbed by scientific evidence because, as all creationists know, scientific evidence is either lies made up by evil scientists, or just plain wrong as 'proven' by the fact that creationist cult leaders say so and it doesn't conform with what a bunch of scientifically-illiterate Bronze Age pastoralists who thought the universe consisted of a small flat planet with a dome over it, made up in their origin myths.

Creationism in Crisis - How The Human Heart Evolved As Humans Adapted To An Active Life-Style

Study on architecture of heart offers new understanding of human evolution - Swansea University

According to research by an international team from Swansea University, Swansea, Glamorgan, Wales and the University of British Columbia, Okanagan, Canada, there is evidence that the human heart has evolved to facilitate the more active life-style of humans compared to their closest relatives, as they diversified.

Humans typically have a much more active life-style with a higher resting metabolic rate compared to chimpanzees. We also have larger brains. As hunter-gatherers, we typically walked and ran far more often and for much longer than do the other apes and we needed to lose the excess body heat this activity generated, so we needed a more hemodynamic heart able to meet those needs, which meant adaptations to changes in the twisting of the left ventricle (LV) - the chamber which pumps oxygenated blood around the body - during systole, and this meant a change in the degree of trabeculation inside the LV.

In the context of heart ventricles, what are trabeculae and what is their function? Trabeculae (also known as trabeculae carneae) are irregular ridges of muscle found on the inner walls of the ventricles of the heart. They play several important roles in the function of the heart:

1. Structural Support: Trabeculae carneae help reinforce the ventricular walls. Their irregular structure provides additional strength and prevents the walls from sticking together during contraction, thereby maintaining the heart's shape and integrity.
2. Facilitation of Blood Flow: The trabeculae carneae create a more turbulent flow of blood within the ventricles, which can help with the efficient mixing of blood and ensure a more thorough contraction and expulsion of blood from the ventricles during systole.
3. Conduction System: Some trabeculae carneae are involved in the conduction system of the heart. For example, the moderator band (a type of trabecula) in the right ventricle contains part of the right bundle branch of the bundle of His. This helps coordinate the contraction of the right ventricle by ensuring that the electrical impulses are transmitted efficiently.
4. Reduction of Blood Stagnation: By creating a complex surface within the ventricles, trabeculae carneae reduce the likelihood of blood stagnation, which can prevent clot formation and improve overall blood flow dynamics.

In summary, trabeculae carneae serve to strengthen the ventricular walls, enhance blood flow, support the heart's electrical conduction system, and reduce the risk of blood clots by preventing blood from pooling in the ventricles.

What is meant by 'ventricular twist'?

'Ventricular twist' refers to the complex motion of the heart's ventricles during the cardiac cycle, particularly during the contraction (systole) and relaxation (diastole) phases. This twisting motion is also known as 'ventricular torsion' or 'ventricular rotation.' Here’s a more detailed explanation:

Mechanics of Ventricular Twist

1. Twisting Motion During Systole: During systole, the ventricles contract to pump blood out of the heart. The base (the top part of the ventricles, near the atria) of the heart rotates in a counterclockwise direction (when viewed from the apex), while the apex (the bottom tip of the heart) rotates in a clockwise direction. This results in a wringing motion, similar to wringing out a wet towel.
2. Untwisting Motion During Diastole: During diastole, the ventricles relax and fill with blood. The previously twisted ventricles now untwist, helping to create a suction effect that aids in the efficient filling of the ventricles with blood.

Significance of Ventricular Twist

1. Efficient Blood Ejection: The twisting motion enhances the efficiency of the heart’s pumping action. By adding a rotational component to the contraction, the heart can expel blood more forcefully and completely.
2. Diastolic Suction: The untwisting or recoil of the ventricles during diastole contributes to the rapid filling phase. This elastic recoil generates a negative pressure that helps draw blood into the ventricles more efficiently.
3. Mechanical Synchrony: The coordinated twisting and untwisting ensure that the contraction and relaxation phases are well-synchronized, promoting optimal cardiac function and maintaining a steady and efficient blood flow throughout the body.
4. Clinical Relevance: Abnormalities in ventricular twist mechanics can be indicative of various cardiac pathologies, such as heart failure, myocardial infarction, or cardiomyopathies. Therefore, measuring and analyzing ventricular twist can provide valuable diagnostic and prognostic information.

Measurement of Ventricular Twist
Ventricular twist can be assessed using advanced imaging techniques such as speckle-tracking echocardiography (STE) or cardiac magnetic resonance imaging (MRI). These techniques allow for detailed visualization and quantification of the rotational mechanics of the heart.

In summary, ventricular twist is a crucial aspect of the heart’s mechanics, contributing to the efficient ejection and filling of blood in the ventricles. It is essential for maintaining optimal cardiac function and can be an important parameter in the assessment of heart health.

The team has shown there is a negative correlation between the degree of trabeculation and LV systolic twist. The inner wall of the LV of a healthy human heart is comparatively smooth. Their results are published in the journal Communications Biology and explained in a Swansea University News release:

An international research team from Swansea University and UBC Okanagan (UBCO) has uncovered a new insight into human evolution by comparing humans’ hearts with those of other great apes.

Despite humans and non-human great apes having a common ancestor, the former has evolved larger brains and the ability to walk or run upright on two feet to travel long distances, likely to hunt.

Now, through a new comparative study of the form and function of the heart, published in Communications Biology, researchers believe they have discovered another piece of the evolutionary puzzle.

The team compared the human heart with those of our closest evolutionary relatives, including chimpanzees, orangutans, gorillas, and bonobos cared for at wildlife sanctuaries in Africa and zoos throughout Europe.

During these great apes' routine veterinary procedures, the team used echocardiography—a cardiac ultrasound—to produce images of the left ventricle, the chamber of the heart that pumps blood around the body. Within the non-human great ape's left ventricle, bundles of muscle extend into the chamber, called trabeculations.

The left ventricle of a healthy human is relatively smooth, with predominantly compact muscle compared to the more trabeculated, mesh-like network in the non-human great apes. The difference is most pronounced at the apex, the bottom of the heart, where we found approximately four times the trabeculation in non-human great apes compared to humans.

Bryony Curry, first author
Centre for Heart, Lung and Vascular Health
School of Health and Exercise Sciences
University of British Columbia, Kelowna, BC, Canada.

The team also measured the heart's movement and velocities using speckle-tracking echocardiography, an imaging technique that traces the pattern of the cardiac muscle as it contracts and relaxes.

We found that the degree of trabeculation in the heart was related to the amount of deformation, rotation and twist. In other words, in humans, who have the least trabeculation, we observed comparatively greater cardiac function. This finding supports our hypothesis that the human heart may have evolved away from the structure of other non-human great apes to meet the higher demands of humans’ unique ecological niche.

Bryony Curry.

A human’s larger brain and greater physical activity compared to other great apes can also be linked to higher metabolic demand, which requires a heart that can pump a greater volume of blood to the body.

Similarly, Higher blood flow contributes to humans’ ability to cool down, as blood vessels close to the skin dilate—observed as flushing of the skin—and lose heat to the air.

In evolutionary terms, our findings may suggest selective pressure was placed on the human heart to adapt to meet the demands of walking upright and managing thermal stress.

What remains unclear is how the more trabeculated hearts of non-human great apes may be adaptive to their own ecological niches. Perhaps it’s a remaining structure of the ancestral heart, though, in nature, form most often serves a function.

Dr Aimee Drane, co-corresponding author
International Primate Heart Project
Cardiff Metropolitan University, Cardiff, UK
And Faculty of Medicine
Health and Life Sciences
Swansea University, Swansea, UK

The research team is grateful to the staff and volunteers who care for the animals in the study, including the teams at Tchimpounga Wildlife Sanctuary (Congo), Chimfunshi Wildlife Sanctuary (Zambia), Tacugama Chimpanzee Sanctuary (Sierra Leone), Nyaru Menteng Orangutan Rescue and Rehabilitation Center (Borneo), the Zoological Society of London (UK), Paignton Zoo (UK), Bristol Zoo Gardens (UK), Burgers’ Zoo (Netherlands) and Wilhelma Zoo (Germany).

Abstract
Although the gross morphology of the heart is conserved across mammals, subtle interspecific variations exist in the cardiac phenotype, which may reflect evolutionary divergence among closely-related species. Here, we compare the left ventricle (LV) across all extant members of the Hominidae taxon, using 2D echocardiography, to gain insight into the evolution of the human heart. We present compelling evidence that the human LV has diverged away from a more trabeculated phenotype present in all other great apes, towards a ventricular wall with proportionally greater compact myocardium, which was corroborated by post-mortem chimpanzee (Pan troglodytes) hearts. Speckle-tracking echocardiographic analyses identified a negative curvilinear relationship between the degree of trabeculation and LV systolic twist, revealing lower rotational mechanics in the trabeculated non-human great ape LV. This divergent evolution of the human heart may have facilitated the augmentation of cardiac output to support the metabolic and thermoregulatory demands of the human ecological niche.

Introduction
Mammals are a remarkably diverse class of vertebrates, capable of inhabiting every major biome on the planet. This diversity is associated with a vast range of environmental stressors and interspecific differences in posture and locomotion, creating very different hemodynamic challenges. Despite this remarkable diversity, the gross structure of the mammalian heart is highly conserved across species; retaining four chambers and a complete interatrial and interventricular septum¹.

Although the gross structure of the mammalian heart is conserved, interspecific features exist. For example, heart shape varies considerably across species, from broad and flat in whales to long and narrow in terrestrial ungulates2. Variation in the cardiac phenotype is also present among closely-related mammals², indicative of evolutionary divergence. While comprehensive data examining cardiac structure and function across the entire Hominidae taxon do not exist, preliminary work suggests that the left ventricle (LV) of adult male chimpanzees (Pan troglodytes) may be morphologically distinct from that of humans³. Prominent myocardial trabeculations, characterized by protrusions of the endocardium into the LV cavity with intertrabecular recesses, were previously observed in adult male chimpanzees³. This trabeculated phenotype differs from the relatively smoother ventricular wall typically observed in healthy humans⁴, suggesting that there may have been species-specific selective pressures on the heart during the evolution of Hominidae³.

Cardiac morphology and function are closely linked⁵; therefore, the discrete structural attributes of the chimpanzee and human LV likely coincide with differences in systolic and diastolic ventricular function. Such interspecific cardiac phenotypes may be the result of selection for the hemodynamic demands associated with each species’ ecological niche (i.e., the habitat and the role a species plays within an ecosystem). Indeed, previous data has shown that resting metabolic rate⁶, physical activity and daily locomotion⁷ are far greater in humans in comparison with other great apes, and so it is not surprising that cardiac output is also comparatively higher in humans³. The larger cardiac output in humans is likely supported by comparatively greater LV systolic and diastolic function (e.g., myocardial rotation and deformation), including LV twist³. LV twist, which is dependent upon the helical angulation of the aggregated cardiomyocytes^8,9,10, is characterized by counter-directional rotation of the LV base and apex during systole. Together with the velocity of LV untwisting during diastole, LV twist helps facilitate efficient filling and ejection of the ventricle, especially during periods of heightened metabolic and thermoregulatory demand^11,12.

The functional advantages associated with a LV capable of greater twist and untwisting velocity, combined with the preliminary data in adult male chimpanzees³, prompt the hypothesis that the human heart has diverged from a trabeculated ancestral phenotype to support the specific metabolic and thermoregulatory demands of the human niche. To test this hypothesis, we compared LV structure across all extant great apes using 2D echocardiography and further explored trabeculation in a subset of post-mortem chimpanzee (Pan troglodytes) hearts. We then compared LV rotation and deformation between human and non-human great apes to explore whether the trabeculated phenotype is associated with differences in LV systolic and diastolic functional mechanics. Our findings point to evolutionary divergence of the human LV away from the phenotype of all other non-human great apes, which may have had important implications for cardiac function in early humans.

Discussion (part of)

[…]

Collectively, the findings of this study support evolutionary divergence of the human LV away from a trabeculated ancestral phenotype, towards a ventricular wall with a proportionately greater compact myocardium. We propose that this adaptive evolution occurred to support the requirements of the human ecological niche, including an augmented cardiac output to facilitate sustained bipedal physical activity, a larger brain, and the associated metabolic and thermoregulatory demands.

Fig. 1: Comparison of left ventricular trabeculation in great apes.

The bullseye plots represent the trabecular:compact (T:C) ratio for each segment of the left ventricle. The outer layer of the bullseye plots represents the basal segments, the middle and innermost layers represent the midpapillary and apical segments of the left ventricle, respectively. Red segments correspond to an average T:C ratio of >2; orange segments correspond to an average T:C ratio >1.5–2; yellow segments correspond to an average T:C ratio of >1–1.5; green segments correspond to an average T:C ratio of >0.5–1; blue segments correspond to an average T:C ratio of <0.05. Echocardiographic images of the parasternal short-axis at the apex are shown at end-diastole. *No data were available for the basal or midpapillary segments in the orangutans due to artifact from laryngeal air sacs. †These T:C ratios compare favorably with other reports in healthy human cohorts, ranging from 0.2 to 0.9^65,66. ‡Anatomical labels have been provided in accordance with the conventional guidelines for cardiac chamber quantification by the American Society of Echocardiography and European Association of Cardiovascular Imaging⁵². However, we note that this clinical convention does not align with the recognized anatomical approach and may result in confusion across disciplines—see ref. ⁶⁷ for further clarification.

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Fig. 2: Graphical representation of the trabecular:compact (T:C) ratio for each segment of the left ventricle in chimpanzees.

The outer layer of the bullseye plots represents the basal segments, the middle and innermost layers represent the midpapillary and apical segments of the left ventricle, respectively. Red segments correspond to an average T:C ratio of >2; orange segments correspond to an average T:C ratio >1.5–2; yellow segments correspond to an average T:C ratio of >1–1.5; green segments correspond to an average T:C ratio of >0.5–1; blue segments correspond to an average T:C ratio of <0.05. Infant age class includes individuals of ≤4 years of age, juveniles between 5–7 years of age, sub-adults between 8-11 years of age and adults ≥12 years of age.

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Fig. 3: Comparison of left ventricular morphology and mechanical indices of ventricular function between chimpanzees and humans.

Shortening along the long axis of the left ventricle (i.e., longitudinal strain) and deformation at the apex (i.e., apical circumferential and apical radial strain) were averaged across a mixed-sex, adult cohort of chimpanzees (n = 136) and represented in maroon. Blue reflects the deformation patterns of a mixed-sex, adult human cohort (n = 34). Dashed line represents aortic valve closure. Gray shading to the left of dashed line represents systole and white represents diastole.

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Fig. 4: Relationship between markers of left ventricular (LV) function and apical trabeculation in the extant Hominidae taxon.

a Peak LV systolic apical rotation, shown in red, in a mixed-sex, adult cohort of humans (male n = 18, female n = 16), chimpanzees (male n = 59, female n = 51), bonobos (male n = 2, female n = 4), gorillas (male n = 4, female n = 6) and orangutans (male n = 10, female n = 6). b Peak LV systolic twist, shown in green, and (c) peak diastolic untwisting velocity, shown in blue, in a cohort of humans (male n = 18, female n = 16), chimpanzees (male n = 47, female n = 43), bonobos (male n = 1, female n = 3) and gorillas (male n = 4, female n = 5). Analyses of LV twist and untwisting velocity were not possible in all individuals, nor any of the orangutans due to artifacts from laryngeal air sacs, hence the reduced sample size. The exponential plateau curve is shown, with the 95% confidence bands represented by the dotted line. The mean and standard error are shown in black for each species.

Curry, B.A., Drane, A.L., Atencia, R. et al.
Left ventricular trabeculation in Hominidae: divergence of the human cardiac phenotype. Commun Biol 7, 682 (2024). https://doi.org/10.1038/s42003-024-06280-9

Copyright: © 2024 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

No crumbs of comfort there for creationists as the authors attribute everything to evolution by natural selection as humans diverged from the other great apes, nor is there any hint of a doubt that such an evolutionary divergence occurred.

The interesting thing from a biologists point of view is how the changes to the human heart reflect changes in our life-style as we adopted an upright gait and a hunter-gatherer life-style, necessitating running and walking long distances with additional demands on our heart to cope with the additional oxygen required and to dissipate the excess heat these activities generated, in addition to the increased demands our large brains were already imposing on our circulatory and thermoregulatory systems.

More work is now needed to understand whether the retention of this degree of trabeculation in the other apes has a benefit or whether it has simply been retained from a common ancestor. If the former, what evolutionary trade-off has there been for humans in losing these benefits?

Evolution News - An Atlas Of The Human Ovary Shows Common Ancestry of Mammals

Ovarian follicle

Human ovarian follicle

First atlas of the human ovary with cell-level resolution is a step toward artificial ovary | University of Michigan News

This piece of research caught my eye, not so much because it refutes creationism with its daft notion of the special creation of humans as separate from all the other animals but because it's reminiscent of the research I used to be involved with in my first profession - a research technician in Oxford University's Department of Human Anatomy.

The research our small group was doing involved the hormonal control of reproduction in guinea pigs, which involved preparing light microscope slides of sections of guinea pig ovaries, and later on, transmission electron micrographs of ovarian tissues.

Like humans, guinea pigs have oestrus cycles where they periodically shed eggs from their ovaries regardless of whether they have mated or not. This is unlike some other mammals which ovulate soon after mating, stimulated to do so by the act of mating. Unlike human females, guinea pigs are only receptive for two or three days before and just after they ovulate. Outside that receptive period, they have a closure membrane that makes penetration impossible.

Unintelligent Design - The Human Curved Birth Canal and Foetal Welfare

Relationship between pelvic depth (i.e. AP length of the pelvis) and spinal curvature as documented in the orthopaedic literature. The pelvis and spine are shown schematically in sagittal view. A Normal spinopelvic relationship where the centre of mass (indicated by the vertical dashed line through the last cervical vertebra, the so-called C7 plumbline) is positioned sagittally above both the hip joints and the superior endplate of the sacrum. B In an anteroposteriorly elongated pelvis (as indicated by the red double arrow) without spinal adjustment, the centre of mass is located behind the hip joints, which compromises the structural stability of upright posture. C To bring the centre of mass back above the hip joints in this elongated pelvis, the sacrum needs to be tilted forward. This leads to an overall increased curvature of the spine, particularly an increased lumbar lordosis and a deviation of the centre of mass from the sacral endplate. Increased lumbar lordosis is associated with multiple orthopaedic disorders, such as spondylolisthesis and disc herniation

Why do humans possess a twisted birth canal? | Universität Wien

A team led by Katya Stansfield from the University of Vienna has shown how the human birth canal evolved as a compromise and was not intelligently designed by an omniscient designer god to be the best solution to the design problem. In fact, it is a shoddy compromise made necessary because the basic human skeleton is an adaptation of the basic quadrupedal vertebrate skeleton and was never designed from the ground up for bipedalism as we would expect of a structure intelligently designed, rather than one evolved from earlier common ancestors with the other great apes and before that, a quadrupedal vertebrate with a horizontal spinal column.

One of the trade-offs was the welfare and survival of the foetus during the birth process. This was put at increased risk in order to ensure the long-term survival of the mother. Creationists might like to think about that as they try to force fit this into their religion with a putative designer god to whom all human life is sacred…

As the University of Vienna press release explains:

Malevolent Designer News - Leaving Nothing To Chance With Alzheimer's Disease

Plasma and brain concentrations of apo B and Aβ.
(A) In vivo PET detection of amyloid binding was used to confirm cerebral amyloid deposition in HSHA mice and their age-matched WT controls. Representative PET and MRI fusion images (coregistered with MRI templates using conventional Fast Spin Echo Sequence T2-weighted sequence) show scan data at 20 to 40 minutes’ post-intravenous administration of [11C] PiB. Each panel (from left to right) illustrates maximum binding potential for [11C] PiB represented by coronal images at −2, 0, 4, and 6 mm from the bregma; indicated by the vertical bar. Plasma (B) and brain (C) levels of apo B, a surrogate marker of TRLs in HSHA and WT control mice, were determined with ELISA. Data are expressed as mean ± SEM. Human and mouse isoforms of Aβ in plasma (D) and brain (E, F) were measured separately with ELISA kits using antibodies specific to each isoform. The data underlying Fig 2B–2F can be found in S1 Data. Aβ, amyloid beta; apo B, apolipoprotein B; HSHA, hepatocyte-specific human amyloid; MRI, magnetic resonance imaging; PET, positron emission tomography; PiB, Pittsburgh compound; TRL, triglyceride-rich lipoprotein; WT, wild-type.

Source: https://doi.org/10.1371/journal.pbio.3001358.g002

Synthesis of human amyloid restricted to liver results in an Alzheimer disease–like neurodegenerative phenotype

According to Creationists, everything about biology and human anatomy and physiology especially, is definitely not the result of natural, evolutionary forces and the operation of random chance. Instead, it is all designed by their reputedly omnipotent, omniscient god who knew exactly what it was designing and designed if for the particular purpose which it serves - which means it is responsible for both the good and the bad in its 'designs', of course.

So, playing at Intelligent [sic] Design advocates for a moment, we have in this scientific paper an example of the sheer mendacious nastiness of Creationism's divine malevolence. It shows how, just to make sure it's victims get Alzheimer's disease in later life, it has designed a mechanism in the liver that manufactures one of the proteins which has been implicated in the progress of this ghastly disease which robs the sufferer of their dignity, their memory, their personality and eventually their life.

The study, published open access in PLOS Biology, was carried out by John Mamo of Curtin University in Bentley, Australia, and colleagues.

According to the press release from PLOS:

Deposits of amyloid-beta (A-beta) in the brain are one of the pathological hallmarks of AD and are implicated in neurodegeneration in both human patients and animal models of the disease. But A-beta is also present in periphereral organs, and blood levels of A-beta correlate with cerebral amyloid burden and cognitive decline, raising the possibility that peripherally produced a-beta may contribute to the disease. Testing that hypothesis has been difficult, since the brain also produces A-beta, and distinguishing protein from the two sources is challenging.

In the current study, the authors surmounted that challenge by developing a mouse that produces human a-beta only in liver cells. They showed that the protein was carried in the blood by triglyceride-rich lipoproteins, just as it is in humans, and passed from the periphery into the brain. They found that mice developed neurodegeneration and brain atrophy, which was accompanied by neurovascular inflammation and dysfunction of cerebral capillaries, both commonly observed with Alzheimer's disease. Affected mice performed poorly on a learning test that depends on function of the hippocampus, the brain structure that is essential for the formation of new memories.

The findings from this study indicate that peripherally derived A-beta has the ability to cause neurodegeneration and suggest that A-beta made in the liver is a potential contributor to human disease. If that contribution is significant, the findings may have major implications for understanding Alzheimer's disease. To date, most models of the disease have focused on brain overproduction of A-beta, which mimics the rare genetic cases of human Alzheimer's. But for the vast majority of AD cases, overproduction of A-beta in the brain is not thought to be central to the disease etiology. Instead, lifestyle factors may play a more important role, including a high-fat diet, which might accelerate liver production of A-beta.

Continuing Human Evolution

Sketch of median artery vessel which supplies blood to the human forearm and hand.

Credit: Professor Maciej Henneberg

Forearm artery reveals human evolution continues – News

Three scientists from Flinders and Adelaide Universities, Australia, have found evidence of continuing human evolution in the increasing occurrence in adults of an artery known as the median artery, in the forearm. The median artery begins as the main blood supply to the developing forearm but normally atrophies in the embryo when the role is taken over by two other arteries - the radial and ulnar arteries.