Incubators That Reflect Wisdom

“ONE of the frustrating features of the fossil record of vertebrate history is that it shows so little about the evolution of reptiles during their earliest days, when the shelled egg was developing.” So laments Life Nature Library’s book The Reptiles on page 37. But getting the egg is only the start. Incubating it is just as frustrating​—fossils fail evolutionists there also.

MOST BIRDS ARE themselves incubators. They brood their eggs with heat from their own bodies. But feathers can be a problem. They are excellent insulators, and very little body heat can get past them to incubate the eggs. Their Creator Jehovah God, not helpless evolution, solved the problem for them in several ways. For many birds it is a built-in answer: brood patches. Several days before the first egg is laid, the down feathers on the breast are molted, then the blood vessels in this area increase in size and number, the skin thickens and swells. As the bird settles on the nest to brood the eggs, it fluffs out its breast feathers and shuffles about until the bare, superwarmed brood patch is next to the eggs. Or brood patches, for some birds have three of them. Once these heat pads touch the eggs, incubation begins.

BUT NOT ALL BIRDS have brood patches that appear automatically. Some have been programmed by their Creator to make their own. Ducks and geese, for example, pluck the down feathers from their breasts to bring their skin in contact with their eggs. Other birds use their feet as incubators. The blue-footed booby wraps its brightly colored feet around its single egg, and the large webs, through which warm blood circulates rapidly, are just as effective as the brood patches of other birds.

WE HEAR SO MUCH about mother love, but when we turn our attention to the emperor penguin, it’s time for father love to take a bow. In the depths of the Antarctic winter, the female lays an egg and immediately returns to the sea to eat. Papa, however, is left holding the egg on his webbed feet​—feet richly supplied with blood vessels and therefore quite warm. He next drapes over the egg a fold of skin that serves as a brooding pouch. It fits over the egg so snugly that the egg remains tucked into its warm incubator “nest” even when papa walks about. Temperatures drop to -76° Fahrenheit (-60° C.), icy blizzards rage for days, but papa faithfully incubates the egg on his feet. Three months, and not a bite to eat! Mama, however, hasn’t forgotten. After the egg hatches, she returns to feed her family with predigested fish from her stomach, then takes care of the chick while papa heads for the sea to feed.

SOME BIRDS USE ready-made hot spots as incubators. The maleo on the Indonesian island of Sulawesi lays its eggs on the slopes of volcanoes, where the ground is permanently heated by volcanic steam. Other maleo on the island use the black volcanic sands at the heads of beaches. They bury their eggs in the sand, which, being black, absorbs heat for incubation.

BUT BIRDS ARE NOT the only ones that use sand as incubators. Sea turtles come up on the beaches at night to dig holes in which to lay their eggs, sometimes as many as 400 or 500 during the breeding season. The Nile crocodile digs a hole in the sand and lays up to 40 eggs. Some three months later when the young hatch, they make little croaking noises, and mama opens the pit and takes her family to water.

REFLECTING EVEN MORE WISDOM than the foregoing, the saltwater crocodile and the American alligator construct quite elaborate incubators. They heap up mounds of branches, reeds, leaves, and decaying vegetable matter near a river or swamp water. In the midst of these three- or four-foot-high (1 m) mounds they lay their eggs and from time to time use their tails to splash water on them. This speeds up the fermentation of the decaying plant mass, which provides the uniformly high temperature needed for hatching the eggs.

BUT AS ELABORATE AS these reptilian incubators are, they fall far short of those constructed by the mallee birds. They are also called the thermometer fowl. They live in arid central Australia, where temperature fluctuations are great, both daily and seasonally. Construction starts at the time of the first autumn rains, as the vegetation used must be wet for fermentation to begin. Both male and female work, but the male does most of the heavy labor. The female, however, will often act as a rather particular supervisor.

THEY DIG A PIT three or four feet deep, fill it with twigs and leaves, heap on more vegetable matter, and top this off with a great deal of sand. The compost below starts fermenting, but it takes four months for the needed temperature of 93.2° Fahrenheit (34° C.) to develop. Only then can egg laying begin. The cock digs a brood chamber in the compost, tests the temperature with his open beak, then steps back for the hen to lay an egg. But no, she has to check the temperature for herself. If she isn’t satisfied, the cock must find a more suitable place in the compost. When she is satisfied and lays the egg, the cock scratches the pit shut again. Every three or four days this procedure takes place, until some 30 eggs have been laid.

ALL OF THIS WHILE the adult birds are tending the mound, digging into its interior where the eggs are, checking the temperature, then filling in the mound again. Depending on the time of day and the weather, they may add sand or remove some, or dig ventilation shafts into the mound, then close them up at the right time. Long hours and hard work, but it limits the temperature variation to no more than 1 degree. Each egg takes 50 days to hatch, each chick digs out of the mound on its own and scampers off, ignored by its parents. Laying, hatching, mound tending​—it all continues simultaneously for 6 or 7 months. With the 4-month period needed at the beginning for the mound to heat up, it means nearly 11 months of continuous labor. And all for producing chicks they totally ignore!

WHAT WISDOM IS REFLECTED in all these various incubators! Yet the animals involved are not wise in themselves. What wisdom they demonstrate is programmed into them by their Creator, Jehovah God. As Proverbs 30:24 indicates: “They are instinctively wise.”

[Pictures on page 14, 15]

Greylag goose

Emperor penguin

Maleo bird

Sea turtle

Alligator

Mallee fowl