The pigment melanin is found in all living kingdoms and in many different structures and forms. When its various functions are examined separately, its behaviors seem disparate and conflicting. It has a clear role in camouflage and sexual display. Other major roles are examined critically. It can act as a sun screen but is not a very effective one. It can also scavenge active chemical species, but this, too, is not done very effectively. It produces active radicals that can (...) damage DNA. It binds to drugs in ways that are either beneficial or deleterious. Aside from camouflage, its other roles can be brought together by a unifying hypothesis as first proposed by Proctor and McGinness nearly 20 years ago. Melanin is envisaged as an energy transducer with the properties of an amorphous semiconductor. It can absorb many different types of energy and dissipate them in the form of heat. However, if the energy input is too great, the output can be expressed in the form of activated chemical species that can damage cellular macromolecules resulting in cell death, mutations and cancer. The protective aspect of melanin in dark skin is seen as resulting from its high concentration and its confinement to ellipsoidal and densely packed organelles that can effectively shield the nucleus. In light skin, its radical nature is seen as potentially participating in the carcinogenic process, particularly when overwhelmed by intense episodes of sunburn. (shrink)

Melanin, and other pigments have recently been shown to preserve over geologic time scales, and are found in several different organisms. This opens up the possibility of inferring colours and colour patterns ranging from invertebrates to feathered dinosaurs and mammals. An emerging discipline is palaeo colour: colour plays an important role in display and camouflage as well as in integumental strengthening and protection, which makes possible the hitherto difficult task of doing inferences about past ecologies, behaviours, and organismal appearance. (...) Several studies and techniques have been presented in the last couple of years that have described ways to characterize pigment patterns. Here, I will review the available methods and the likely applications to understand past ecologies. A golden age of colourized dinosaurs and other animals is now dawning upon us, which may elucidate the nature of ancient predator prey interactions and display structures.Also watch the Video Abstract. (shrink)

The discovery of traces of a blood meal in the abdomen of a 50‐million‐year‐old mosquito reminds us of the insights that the chemistry of fossils can provide. Ancient DNA is the best known fossil molecule. It is less well known that new fossil targets and a growing database of ancient gene sequences are paralleled by discoveries on other classes of organic molecules. New analytical tools, such as the synchrotron, reveal traces of the original composition of arthropod cuticles that are more (...) than 400 my old. Pigments such as melanin are readily fossilized, surviving virtually unaltered for ∼200 my. Other biomarkers provide evidence of microbial processes in ancient sediments, and have been used to reveal the presence of demosponges, for example, more than 635 mya, long before their spicules appear in the fossil record. Ancient biomolecules are a powerful complement to fossil remains in revealing the history of life. (shrink)

The discovery of fossil melanosomes has resulted in a wealth of research over the last 7 years, notably the reconstruction of colour in dinosaurs and fossil mammals. In spite of these discoveries some authors persist in arguing that the observed microbodies could represent preserved bacteria. They contend that bacteria fossilise easily and everywhere, which means that one can never be certain that a microbody is a melanosome without an extraordinary burden of evidence. However, this critique mischaracterises the morphological and structural (...) evidence for interpreting microbodies as fossil melanosomes, and hence the basis for using them in reconstructing prehistoric colours. The claims for bacterial omnipresence in the fossil record are themselves not supported, thus tipping the scales strongly towards melanosomes in the bacteria‐versus‐melanosome controversy. (shrink)

Challenged by Lord Kelvin's claims that earth and sun were too young to give evolution sufficient time to do its work, especially in the human case, where care for the weak blunts the edge of natural selection, Darwin leaned on Lamarckian thoughts to accelerate the process. The mental and moral traits crowning human distinctiveness, he urged, arose through sexual selection. But promiscuity, infanticide, early betrothals, and female drudgery undermined these effects in “savage races.” In the inevitable decline and ultimate extinction (...) of the “melanin races” Darwin believed he could observe human evolution underway before his eyes. (shrink)

Recent studies have yielded new insights into the critical importance of adequate vitamin D3 intake and metabolism. Investigations of the actions of 1,25‐dihydroxyvitamin D3 (calcitriol) on novel target tissues has revealed that this hormone has functions other than its recognized action in regulating blood calcium and phosphate levels. Reports have characterized calcitriol receptors and activities in organs and tissues as diverse as pancreas, skeletal and heart muscle, blood cells, brain, skin, pituitary, parathyroid, kidney, bone and intestine. These studies suggest functions (...) for calcitriol as varied as the regulation of insulin and prolactin secretion, muscle contractility, immune cell metabolism, melanin synthesis and differentiation of blood cells. This information may ultimately help us to understand the etiologies of several kinds of organ dysfunction and lead to the development of tissue‐specific agents for new therapies. (shrink)

One of the fundamental fallacies of racism is the confusion between biological accidents such as: body, colour, environment, size, shape, and melanin with metaphysical essences like; soul, mind, and intellect. Personness for instance is an essential category that does not depend on the above accidental attributes. Since time immemorial, racism has been reinforced by deeply entrenched social structures. These structures are the offspring of both overt and covert racism. Structural racism is epitomised by ideologies that have been well disguised (...) under facades of science. These ideologies include: Eugenics, Social Darwinism, Modernisation theory and Neo-liberalism. This paper critically analyses the religious, political, psychoanalytic, historical and economic construction of structural and institutional racism that reinforces honorary whiteness in the African social milieu. The paper argues that the purpose of racism is constructing Black and Brown people as entities in dire need of White Saviourism and White Paternalism. This consequently culminates into imperialism, neo-colonialism, subjugation and exploitation. The paper further contends that racism is crystalised through mental colonialism which rides on socially constructed racial binaries, dichotomies and hierarchies such as: White (righteous) and Black (evil), North (top) and South (bottom), West (Sun-rise) and (Sun-set), Aryan and Honorary Aryan, White and Honorary White. (shrink)

One of the fundamental fallacies of racism is the confusion between biological accidents such as: body, colour, environment, size, shape, and melanin with metaphysical essences like; soul, mind, and intellect. Personness for instance is an essential category that does not depend on the above accidental attributes. Since time immemorial, racism has been reinforced by deeply entrenched social structures. These structures are the offspring of both overt and covert racism. Structural racism is epitomised by ideologies that have been well disguised (...) under facades of science. These ideologies include: Eugenics, Social Darwinism, Modernisation theory and Neo-liberalism. This paper critically analyses the religious, political, psychoanalytic, historical and economic construction of structural and institutional racism that reinforces honorary whiteness in the African social milieu. The paper argues that the purpose of racism is constructing Black and Brown people as entities in dire need of White Saviourism and White Paternalism. This consequently culminates into imperialism, neo-colonialism, subjugation and exploitation. The paper further contends that racism is crystalised through mental colonialism which rides on socially constructed racial binaries, dichotomies and hierarchies such as: White (righteous) and Black (evil), North (top) and South (bottom), West (Sun-rise) and (Sun-set), Aryan and Honorary Aryan, White and Honorary White. (shrink)

Round to elongate microbodies associated with fossil vertebrate soft tissues were interpreted as microbial traces until 2008, when they were re‐described as remnant melanosomes – intracellular, pigment‐containing eukaryotic organelles. Since then, multiple claims for melanosome preservation and inferences of organismal color, behavior, and physiology have been advanced, based upon the shape and size of these microstructures. Here, we re‐examine evidence for ancient melanosomes in light of information reviewed in Vinther (2015), and literature regarding the preservation potential of microorganisms and their (...) exopolymeric secretions. We: (i) address statements in Vinther's recent (2015) review that are incorrect or which misrepresent published data; (ii) discuss the need for caution in interpreting “voids” and microbodies associated with degraded fossil soft tissues; (iii) present evidence that microorganisms are in many cases an equally parsimonious source for these “voids” as are remnant melanosomes; and (iv) suggest methods/criteria for differentiating melanosomes from microbial traces in the fossil record. (shrink)