Evolution Suggests Humans and Insects evolved Together



Insects and men evolved together, live together, and have a lot in common.  Scientists estimate that there are about 8.7 million species on Earth, only 2 million or so that have been officially identified.  So over 6 million of them have not yet been ID’d. Nevertheless, researchers suggest, humans and insects are in it together.

But there could be a lot more insects hanging around out there.

The International Institute for Species Exploration at Arizona State University in Tempe wants to find 10 million additional species by 2063.  Insects frequently make it to the top ten list of species and rated best by taxonomists, the ones who categorize and tag each species.   Past titleholders have been wasps, millipedes and tarantulas.  More recent winners include Lucihormetica luckae, a cockroach that glows in the dark that was spotted 70 years ago in Ecuador and may already be extinct, and Semachrysa jade, a green lacewing insect, discovered liked a Hollywood starlet from a photo posted on Flickr.

The word “insect” is derived from the Latin insectare, “to cut up.” This is presumably because insects are “cut” into three sections—head, thorax and abdomen—and not because the Romans thought they were funny.

Insect fossils dating back to the Carboniferous period (359.2 to 299 million years ago) exhibit wings and other features, suggesting they’ve been around for tens of millions of years.  Arthropods like scorpions, centipedes, and millipedes probably got onto land about 400 million years ago. This was the same period in which our ancestral tetrapods, basically fish with lungs, climbed out of the water.  Although arthropods may have existed 150 million years before insects, invertebrates (animals that don’t have spines) and vertebrates (animals that do) appeared about the same time, 500 million years ago.  Prior to that we have flatworms (circa 550 million years) that were the earliest animals with brains.  An acorn worm (540 million years ago) has a circulatory system, a heart, kidneys and gill-like structures for breathing.  It may be the evolutionary link between vertebrates and invertebrates.

The similarities between all known organisms, living or extinct, suggest a common ancestor from which all species have evolved.  We pretty much know that it all started with prokaryotes, unicellular organisms like bacteria and archaea, which emerged about four billion years ago.

Cnidarians, arising about 580 million years ago, were the first animals with a definite form and shape, as well as nerves and muscles, which allowed them to move.  This was also the time when animals started developing eyes.

The cladistic (taxonomic) line of descent of man from eukaryotes (cells with nuclei) through great apes to Homo sapiens (modern humans), includes animalia, the kingdom of living things that differ from plants in possessing the capacity for spontaneous movement and rapid motor response to stimulation.    So we and insects are in it together, at least evolutionally speaking.

Insects and men have many characteristics in common.  An insect has a nervous system, made up of a brain and a ventral nerve cord. It’s been verified that insects feel pain.  In 2003, scientists found that the larvae of fruit flies rolled away from the touch of a heated probe but didn’t react to an unheated one.  An insect also has an alimentary canal and salivary glands.

Insects share with humans the senses of vision and hearing, but insects best us in the area of chemoreception, which is the physiological response of a sense organ to a chemical stimulus resulting in our ability to taste and smell.  Insects make us of semiochemicals.  Semiochemicals are message-carrying chemical, such as pheromones and kairomones.  An insect could use semiochemicals to find out where her mate had before he got home.

A study in 2012 found that distinct patterns of gene activity in molecular pathways in bees showed similarities to those in thrill-seeking humans.  When a colony outgrows its living space, a few bees, known as nest scouts, take off to hunt for new digs.  They are also the kind of bees that act as food scouts.  Adventurousness is a sign of personality.

If bees want novelty, just like humans, the unanswered question is:  do bees get bored?

Insects were definitely ahead of humans in making weapons.  As plants evolved chemical defenses against insects, insects developed mechanisms that not only resisted plant toxicity but retained it to use against predators.

Insects are similar to humans in what are regarded as “social” behaviors.  These include parental care of the young and communal nests.  But ethnologists do not regard a creature as eusocial (truly social) unless there are two other behaviors present:  a division of labor in which sterile individuals work for the benefit of the reproductive ones; and an overlap of generations in which offspring contribute to the labor of the colony while their parents are still alive.  Alternative three would not go over well with the population.  And parents bemoan the lack of a generational overlap of responsibility in their teenaged progeny.

Alas, we don’t get along that well with bugs.  Actually, “bugs” is the name for certain groups of insects that exhibit obnoxious behavior.    First of all, we consume them.  Apes eat insects, such as ants, along with leaves, fruit, tree bark, seeds, and occasional small animals. And we know that insects are regarded as a delicacy in some parts of the world.  Vietnamese, at least those in Hanoi, like deep-fried scorpions.  Australian Aborigines eat grubs.  Fried grasshopper is a favored dish in some Southeast Asian countries.   There are wasp crackers, bee larvae casseroles, and silkworm pupae soup.

On the other hand, most people regard them as pests.  Besides stomping on them whenever they make an appearance on our kitchen floors, we try to eliminate them with pesticides.

Approximately 5.1 billion pounds of pesticides are used each year in the United States. There are statistics indicating that some form of pesticide is used in 78 million out of the 105.5 million households in the U.S.  Over 20,000 pesticide products, with more than 1,055 active ingredients, are being marketed in this country.

We know that pesticides are inimical to our health.  Pesticides can mimic hormones to cause reproductive problems.  Studies on non-Hodgkin lymphoma and leukemia showed that such illnesses are linked to pesticide exposure.  Pesticides also cause birth defects, fetal death, and neurodevelopmental disorder.

In any event, using poisons to kill insects didn’t work out too well for plants.

We’re also getting proficient in exploiting insects.  Wasps can be trained in minutes to follow specific smells with the olfactory sensors in their antennae in order to detect chemicals in the air.  They could be used to search for explosives, toxic chemicals, and even fungi on crops.  In other words, insects could replace sniffing dogs.

Just as we are finding insects with human characteristics, people exhibit insect behavior.  The “Human Fly,” was the nickname for stunt entertainers who scaled the exteriors of tall buildings in the U.S., mainly between 1910 and 1977.

The best connection between insects and humans is found at the movies.  There have been at least fifty films in cinematic history featuring insects, especially killer insects, including Them (1954—ants), Eight-Legged Freaks (2002—spiders), They Nest (2003—cockroaches), and Ticks (1983).

We really like it when humans turn into bugs.  Scientist David Hedison in 1958’s The Fly acquired the head and antenna of a fly.  Meanwhile the fly gained a human head and arm.  A fly caught in a teleportation machine made Jeff Goldblum completely mutate from homo sapiens to diptera in 1986’s The Fly. And don’t get me started on Spiderman.

With this preponderance of evidence, it appears that researchers may be right; perhaps evolution does suggest that humans and Insects evolved together. Sorry Darwin.

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