Crows are known to hide food. If they suspect someone is watching, they’ll use subterfuge to move it elsewhere. They can solve multi-step problems and understand abstract analogies too, pairing objects with notional relationships to each other such as a square and a circle – all this with a brain lacking a neocortex and smaller than a fingertip.
If the braininess of octopodes and ravens fails to impress, consider certain plants, particularly the mimosa. Native to parts of Central and South America, the mimosa plant is small, with paired leaflets along each stem. Touch one of the leaves and – presto! – the entire plant folds its leaves.
Several hundred years ago, French botanist Rene-Louiche Desfontaines was astonished at this reactivity and carried a plant round Paris in his carriage, showing others. This happened at a time, it must be remembered, when the prevailing Aristotelian view of plants regarded them as barely alive. Touch-sensitive and insectivorous plants and their ability to move quickly, have been long regarded as truly enigmatic.
In 2013, Stefan Mancuso and Monica Gagliano, working at the University of Florence, sought to replicate Desfontaines’s findings. Mancuso developed a means of testing mimosas, with a controlled 15 centimeter fall onto a padded surface. As expected, on falling each mimosa folded its leaves, not learning from its fall, at least not right away. Plants recovered after this, but responded in like fashion to a fall later in the day. On repeated drops at five to 10 second intervals, the mimosas seemed to figure things out, however, no longer closing their leaves.
Gagliano let her plants rest three days and repeated her experiments. In her words6:
“Like seasoned little base jumpers, these plants continued to disregard the drops as they had learned during their training, and by ignoring it now, they were showing me they could remember the drop flawlessly … They had the facility of memory and their behavior was not hardwired in DNA but learned.”
The notion of plant memory has been slow to gain acceptance but workers have found that drought, temperature extremes, excessive salinity and herbivore attack can all elicit responses that we would regard as memory. Just where memory resides in plants is unknown but would seem to involve calcium channels and hormones. Whether all plants have memory is as well unknown, but reasonable, given all organisms’ common needs for nutrition, habitat and survival sufficient for reproduction.
I think that in our search for intelligent, unexpected life we may miss out if we don’t look in our own backyards. Evolution, as biologist Stephen Jay Gould would remind us, is both quirky and contingent. Given enough time, anything can happen, and one day it may behoove us to place some other being at the top of our refurbished tree-of-life diagrams.
It may all happen close to home.
Editor’s note: The views, perspectives and opinions in this article are solely the author’s and do not necessarily represent those of the AMA.
Banner photo credit: Pat Josse, Pixabay.com