It had all the hallmarks of a bad horror film. A mad scientist transplanting a section of human DNA onto the leg of a fruit-fly… It was doomed to end in comic failure, of course…

But it didn’t. The scientist wasn’t mad… and what happened was the most remarkable thing: a new perspective on genetics that adds another dimension to the way life and consciousness evolve in the universe…

The story begins more than a hundred years ago in the USA. Scientist Mildred Hoag was what we would now call a geneticist; but back then the word hadn’t been invented, though the concept of ‘units of inheritance’ was widely discussed amongst biologists.

Crick, Watson and Rosalind Franklin’s spiral of DNA was more than fifty years into the future.

The re-discovery of Mendel’s pioneering study of the mid 19th century on the inheritance of the humble pea plant had cast new light on how such units of inheritance worked. Mildred Hoag was on the trail of something important. She was studying why some fruit flies had underdeveloped eyes, rendering them practically blind. She knew, from statistical evidence, that the degraded eyes of her fruit flies had been passed down as part of what we would now call their genetic inheritance. For each inherited characteristic, there were two units of inheritance, one from each parent. Today, we know these as genes.

Humans and the humble fruit fly might appear to have little in common. Yet, in the type of fly known as Drosophila, approximately 60 percent of the fly’s genes can also be found in humans in a similar form. Fruit flies are tiny and easily housed. Research with Drosophila therefore provides important models of how a genetic development process is likely to unfold in humans – particular with respect to the treatment of such conditions as cancer.

Mildred Hoag was the first to discover this inherited link in the fruit fly. She named the damaged unit of inheritance ‘Eyeless’. Later, in the rapidly developing world of genetics, it was known as the Eyeless gene… which, in the light of what was to come, was ironic in the extreme…

Hoag published her findings in the 1915 American Naturalist Magazine, but it gathered little attention.

80 years later, student Rebecca Quiring was finishing her PhD with a study of a potentially defective gene in mice known as Small Eye. A vital part of her study was to determine the gene sequence, which she announced in triumph was ‘GTACG’… and then she stopped in amazement. She knew from the history of her science that Mildred Hoag’s Eyeless gene for fruit flies had been shown to have the same sequence. But that wasn’t all…

The human master gene for the eyeball is known as Pax-6. It is responsible for the entire embryonic development of the eye, switching other ‘transcription factors’ on and off as it literally orchestrates each layer of the eye: retina, skin of the cornea, then the lens and finally the iris.

Just writing this makes me think we know very little of the real power of genes…

And now the shocker: Pax-6 has the same sequence – GTACG – as Eyeless and SmallEye. They, and the human Pax-6 master gene were the same entity…

Which brings us to our ‘mad scientist’. In a report published in the UK journal Science, researchers Georg Halder, Patrick Callaerts and Walter J. Gehring detailed how they had successfully triggered the Eyeless gene to begin development of a fruit fly eye in the legs of one of their flies. They said the out-of-place eyes contained the entire eye structures, including cornea, pigment and photoreceptors, the cells that respond to light. That was dramatic enough, but they went on to trigger the human eye gene (Pax-6) on fruit flies’ legs in the same way. Again the process was successful.

You’re probably reeling in horror at the thought of a human eye staring at you from the tiny legs of a fruit fly! Indeed, the New York times ran with the headline:

‘With new flies, science outdoes Hollywood’

But the result was far more dramatic and far less horror-filled than that. The human Pax-6 gene, transplanted into the fruit fly, begun a development of a… fruit fly eye…

Patrick Callaerts describes it this way: ‘The Pax-6 master gene switches on a developmental pathway that makes the eyes for that species.’ It ‘talks to the host and says,”I understand the information coming from the human Pax-6 and I will interpret it according to the needs of my fruit-fly!”‘

Pax-6 is one of a growing number of identified Master Genes. Like the director of a complex Scottish dance, it orchestrates group of dancers, bringing them into the core of the dance when needed, then resting them when they are not. Pax-6 develops at a very early time in the embryo, when the brain is simply a tube waiting to grow a nervous system. Pax-6 is that fundamental in human development, as though the ability to see is a separate and whole ‘gift’ to mankind.

Philosophers have long considered the literal and metaphorical use of ‘light’ as analogous to both understand and wisdom. The universe began its life in the explosive light of the Big Bang.

Wherever you find eyes, you find Pax-6. But is it just sight that is orchestrated by this master gene?

The latest research on marine life show that Pax-6 is present on the underside of the ‘feet’ of starfish. The implications are that is also associated with touch and – by virtue of its ability to detect ‘scents’ in the water – with what we would view as taste and smell. Could it be that Pax-6 actually expresses and controls our entire sensory mechanism – the very basis of our experienced consciousness?

We will probably have the answers to these questions in the next few years. If this possibility is revealed to be true, then Pax-6 as the entire sensory mechanism feeding the brain with experience may well turn out to be a ‘gift from the Gods’ after all…

(Author’s note: my interest in this was sparked by a BBC series of podcasts names ‘Ingeneously’.)

©Stephen Tanham 2021

Stephen Tanham is a Director of the Silent Eye, a journey through the forest of personality to the dawn of Being. and

12 Comments on “An Eye for the Universe?

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