BBC article: New Caledonian crows show how technology evolves:
Tool-making crows have allowed us to see the first foundations of a technological breakthrough.
New Caledonian crows spontaneously make hooks out of plant material, using them to “fish” for grubs and spiders.
Experiments have now revealed that these hooked tools are 10 times faster at retrieving a snack than the alternative tool – a simple twig.
Measuring the hooks’ effectiveness tells scientists something about what drove this tool-use to evolve.
Beyond that, the scientists say the insight has provided them a first glimpse of the “evolution of a new technology” in the animal kingdom.
The findings are published in the journal Nature Ecology and Evolution.
These crows are the only animals known to make hooks.
See here: https://www.nature.com/articles/s41559-017-0429-7