Mars unit induced neurosystem cancer

The nervous-system cancer caused by Martian units was a progressive plague of the Fifth Men, arising because human tissues had never fully assimilated the units used for telepathic communication. As general ill health favored their uncontrolled proliferation, the disease spread across generations, making the inherited means of communication a source of growing danger and fear.

Biological Cause and Spread

The disease emerged from an incompatibility built into the Fifth Men: their tissues had never perfectly assimilated the Martian units that enabled telepathic communication. When the population’s overall health deteriorated, those units proliferated without control, producing what the narrator characterizes as a cancer of the nervous system. The account describes the mechanism and its broad consequences but does not specify a treatment or a cure for this plague.

The illness increased century by century. Its reach extended beyond those who contracted it: people who remained free of the sickness still lived in constant fear of madness. In this way, the disease affected the population both as a physical epidemic and as a pervasive threat to mental security.

A Civilization Under Strain

The nervous-system plague formed part of a wider crisis. The Fifth Men were already facing the decay of their digestive organs and the effects of devastating heat; the narrative presents these troubles together as pressures on an increasingly enfeebled population. Within a thousand years, the once-populous arctic and antarctic islands were almost deserted. Of every hundred great pylons, scarcely more than two remained inhabited, and those shelters held only a few plague-stricken, dispirited survivors.

Declining population and health accompanied a broader loss of capacity. Each brief generation was less well developed than its parents; intelligence declined, education narrowed, and contact with the past became impossible. Art lost its significance, philosophy its hold, and applied science grew too difficult to manage safely. Disasters caused by unskilled control of sub-atomic power helped foster a superstition against altering nature. Books, instruments, and other cultural treasures were burned, leaving only durable buildings and isolated island communities. The account does not attribute each stage of this collapse to the nervous-system disease alone, but places the plague among the afflictions of the civilization’s decline.

Adaptation and the Loss of Telepathy

After many thousands of years, human nature began to adapt to the climate and poisoned water. A new variety of the fifth species also appeared without the Martian units. The race consequently recovered a measure of mental stability, but at the expense of telepathy, which humanity would not regain until almost the last phase of its career.

This later change marks a reversal in the disease’s central biological condition: the units associated with telepathic communication were absent from the new variety, and mental stability returned. The recovery was limited. The earlier civilization’s glory had vanished, and the account passes over the intervening ages before turning to noteworthy events again. The plague therefore stands not only as an epidemic, but as part of a long transition in which survival came with the loss of a defining faculty.