One of the most useful ideas in the paper appears in Figure 3 and Table 2.
There is no single “domestication pathway.”
The authors distinguish seven broad pathways.
Think of them as different evolutionary roads through which plants entered human economies.
Ecosystem engineering
Sometimes people did not remove plants from their ecosystems.
They modified ecosystems around useful plants.
Long-lived trees, palms and pandanus provide examples.
Instead of creating fields, humans could manipulate forests, wetlands or other landscapes to favour useful species.
Oil palm, Brazil nut, sago palm and enset fit aspects of this pathway.
In such systems, the landscape itself becomes partially domesticated.
Ruderal pathway
Some plants thrive around human disturbance.
Camps, paths, waste heaps and cleared ground create new habitats.
Certain plants followed humans into these environments before anyone deliberately cultivated them.
Squash, bottle gourd and other species may partly reflect this pathway.
They began as ecological fellow travellers.
Tuber pathway
Cassava, potato, sweet potato, taro and yams exemplify systems centred on underground storage organs and vegetative propagation.
Their biology produces very different domestication dynamics from cereals.
Grain pathway
This is the pathway most people associate with agriculture.
Annual plants are repeatedly grown from seeds and harvested for seeds.
Wheat, barley, rice, maize, peas, lentils and soybean belong here.
Traits such as non-shattering, reduced dormancy and seed enlargement become particularly important.
Segetal pathway
Here the story becomes delightfully circular.
Some plants began as agricultural weeds.
They adapted to crop fields.
Humans later started cultivating the weeds themselves.
Oats, rye, kodo millet and fonio provide examples.
Today's crop could literally be yesterday's weed.
Fibre pathway
Established crops or weeds could later undergo directed selection for a completely different purpose.
Cotton, flax, hemp, jute and ramie became increasingly important for fibre.
This pathway differs from the earliest food domestications because societies already possessed agricultural knowledge and could conduct more directed selection.
Fruit-tree pathway
Fruit trees entered existing agricultural economies later in many regions.
Grapes, olives, dates, figs, citrus and peaches often involved long-lived perennials followed eventually by propagation using cuttings, grafting and related methods.
Why seven pathways matter
These pathways prevent us from forcing every crop into the wheat model.
Domestication depends on plant biology.
A tree behaves differently from a cereal.
A tuber behaves differently from a seed.
A weed entering an existing field system experiences different pressures from a wild species being cultivated for the first time.
There was no single agricultural revolution.
There were many overlapping evolutionary experiments.
################################################################################
Further reading: This post is inspired by and draws on Dorian Q. Fuller, Tim Denham, and Robin Allaby, “Plant domestication and agricultural ecologies,” Current Biology 33, no. 11 (2023): R636–R649, doi:10.1016/j.cub.2023.04.038. Read the original article in Current Biology
For a classic and highly readable perspective on why plant domestication arose in some regions but not others, see Jared Diamond, Chapter 8, “Apples or Indians: Why Did Peoples of Some Regions Fail to Domesticate Plants?”, in Guns, Germs, and Steel: The Fates of Human Societies (W. W. Norton, 1997), pp. 131–156. Read “Apples or Indians” View Guns, Germs, and Steel on Google Books
################################################################################
No comments:
Post a Comment