As new discoveries are made, the scientific story of human evolution constantly changes. Debate continues on our historic movement across the globe and the exact origins of a number of populations.
There are two reasonable certainties. Modern humans first evolved on the African continent and the differences between all current populations is small.
Of more than 20,000 genes in the human genome, only three are known to directly control skin colour. The evolution of our brain shape and size is shared across humanity, a reaction to developing emotions, memory, using tools and language.
Whilst immunity from certain diseases varies regionally, the genes underlying immunity are more or less the same, as are almost all core building blocks. From a dermatological viewpoint, variations are subtle but deserve attention.
Controlling the melanin levels which shade human skin involves actions below the surface, in cells called melanocytes. People with darker skin tend to have a greater number, along with differences in haemoglobin and tissue formation.
Additional genes are involved in regulating pigmentation levels and mutations can occur, causing pigmentary disorders. They are generally classified as hyperpigmentation, hypopigmentation, or a combination of both.
This is the primary cause of conditions such as melasma, or vitiligo but even without mutation, darker skin can react differently to damage, surgery, or treatment. Careful consideration needs to be given.
The same applies to diagnosing a range of conditions, from eczema, to cancer, where symptoms may vary visually across skin colours. Wherever you are, finding a dermatologist with experience of this is essential.
Even so, whilst the prevalence and treatment of skin conditions can change according to colour, the vast majority are seen in all of us.
The Mosaic Of Humanity
Medical requirements need to be individual but in most senses, classifying humans through the colour of their skin makes no more sense than using shoe size. There is no rational, geographical picture to suggest otherwise.
On our continent of origin, the darkest skin tends to be in eastern Africa, the lightest in southern areas and diversity is widespread. Overlaps with the people of Europe and Asia remain common, on genes related to skin colour.
Modern humans have been around for 200,000 years, yet the appearance of pale skin only occurred 6000 to 8000 years ago, perhaps a little earlier in the far north. An evolutionary reaction to a need for greater vitamin D synthesis.
Neither was this a simple change in a static population. European heritage largely derives from mass migrations by people from the Near East, or Eurasia, complex genetic transfer happened across our planet.
Other minor changes took place, lactose tolerance, again related to vitamin D and natural sugars. Variations continue to occur, increasing numbers are being born with no wisdom teeth, the vein structure in our arms may be changing.
Populations can be shaped by their diet and environment but in a secondary way. Beneath these minor signs, we are essentially the same.
Personal Medical Support
Our skin is a fine, sensitive organ and unique to each of us. As our DNA proves, we have all had a slightly different evolutionary journey, our age and environment will vary, diagnosis and treatment need to be personal.
Skin colour can be a factor, for aspects such as reaction to treatments, the healing process, or the visual effect a condition has. The latter can also make certain conditions, such as vitiligo, far more distressing on darker skin.
A good dermatologist will understand each factor and act accordingly, for safety and effective care. Success in dermatology for darker skin still comes from appreciating the scientific reality, we all have far more similarities than differences.