Here’s another potentially interesting example, based on your article here and this Vox article.
Dan Fergus, a researcher that works with Menninger, estimates that the average person has between 1.5 and 2.5 million mites, but no one really knows.
You wrote:
No formal count has been made of the number of neurons in a springtail, but Tomasik compares its body size to a fruit fly and concludes that if neurons scale linearly with body size between the two, a springtail has about 5800 neurons.
(The number is taken from Brian Tomasik’s article here.)
5,800 might be an overestimate for mites, if they’re much smaller, but I would assume mites have at least as many neurons as C. elegans, 302. Combining the estimate for the number of mites and the estimate for the number of neurons per mite, it looks like at least 0.5 billion neurons from mites on your body, but maybe up to around 10x more. The human brain has ~86 billion neurons. So at least around 0.6% of the neurons in or in close proximity to your body are not your own, but invertebrates’. I wonder what this would look like if you include the mites on your bed, in your room, or your whole home. Could the number of neurons in a house be in the same order of magnitude for human neurons and mite neurons?
If we assumed moral weight was exactly proportional to the square root of whole nervous system neuron count, then the 1.5-2.5 million mites on your body would have at least 80x as much moral weight as you.
I think densities of mites in soil are typically in the range 10^3 to 10^5 per square meter. For example, see the Brady (1974) and Curl and Truelove (1986) numbers here.
In 2016, I used my microscope camera to look for dust mites around my own house during the summer, and I mainly only found them in areas with lots of accumulated skin flakes. Even in the flake patches, they didn’t seem dramatically more densely concentrated than the mites I filmed in the soil outside my house. Of course, this is just one data point. (Also, maybe I could only see the biggest ones? But that would apply to both indoor and outdoor mites.)
I think densities of mites in soil are typically in the range 10^3 to 10^5 per square meter. For example, see the Brady (1974) and Curl and Truelove (1986) numbers here.
Table S4 of Rosenberg et al. (2023) has data on the density of soil mites (acari), springtails (collembola), ants (formicidae), termites (isoptera), and other arthropods. Here is a sheet with the numbers.
Here’s another potentially interesting example, based on your article here and this Vox article.
You wrote:
(The number is taken from Brian Tomasik’s article here.)
5,800 might be an overestimate for mites, if they’re much smaller, but I would assume mites have at least as many neurons as C. elegans, 302. Combining the estimate for the number of mites and the estimate for the number of neurons per mite, it looks like at least 0.5 billion neurons from mites on your body, but maybe up to around 10x more. The human brain has ~86 billion neurons. So at least around 0.6% of the neurons in or in close proximity to your body are not your own, but invertebrates’. I wonder what this would look like if you include the mites on your bed, in your room, or your whole home. Could the number of neurons in a house be in the same order of magnitude for human neurons and mite neurons?
If we assumed moral weight was exactly proportional to the square root of whole nervous system neuron count, then the 1.5-2.5 million mites on your body would have at least 80x as much moral weight as you.
I think densities of mites in soil are typically in the range 10^3 to 10^5 per square meter. For example, see the Brady (1974) and Curl and Truelove (1986) numbers here.
In 2016, I used my microscope camera to look for dust mites around my own house during the summer, and I mainly only found them in areas with lots of accumulated skin flakes. Even in the flake patches, they didn’t seem dramatically more densely concentrated than the mites I filmed in the soil outside my house. Of course, this is just one data point. (Also, maybe I could only see the biggest ones? But that would apply to both indoor and outdoor mites.)
Hi Brian.
Table S4 of Rosenberg et al. (2023) has data on the density of soil mites (acari), springtails (collembola), ants (formicidae), termites (isoptera), and other arthropods. Here is a sheet with the numbers.