Life Across the Pole

Nearly 5,000 miles from familiar forests, the traveling New Zealand naturalists were delighted to find that they might well have been tramping their own woodlands. There in the rain forests of southern Chile were vast stands of beech, remarkably similar to the trees of their native land. The damp Chilean glades were greenly upholstered with ferns and mosses almost exactly like those that grow in Australasia. Even swarming insects looked the same as the insects of home. How did delicate plant and insect life ever make the difficult migration across great southern oceans or the hostile icecap of Antarctica?

There are a couple of possible answers, says Zoologist Martin Holdgate, who led the Royal Society's recent expedition to southern Chile. In the British magazine New Scientist, Holdgate traces the probable biological routes between the temperate lands on the opposite sides of the South Pole. Water-resistant seeds of a few plants may have ridden the ocean currents that flow around Antarctica from west to east, he points out, and the dust-small spores of ferns may have been carried far by the prevailing westerly winds. But most plants and insects of the far southern lands cannot survive long sea or air voyages. The major crossings must have been made in some other way.

It is far more likely, Dr. Holdgate believes, that far-southern forms of plant and animal life spread across Antarctica and the chains of islands that fringe it. Today Antarctica is impassable to higher plants or insects, but fossil evidence shows that 10 million years ago, it had a temperate climate and was covered with forests characteristic of the modern South Temperate Zone. Plants and insects capable of crossing moderate water gaps could have used Antarctica as a bridge between New Zealand and Australia on one side and South America on the other. Some of the flora and fauna may even have evolved in pleasant Antarctic valleys that are now covered by two miles of ice.

Some plants common to both sides of the South Temperate Zone are apparently incapable of crossing even modest water gaps, but if they were in existence 150 million years ago, they probably did not need to. Holdgate points out that in those days, Australia, New Zealand, Antarctica and South America were probably jammed close together. The primitive plants that grew on outlying parts of this great ancient land had only to last out the seasons while the continents drifted northward and moved them and their home thousands of miles apart.

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