HBD is human biodiversity, which is considered by some on the left to be a euphemism for "black people aren't as clever as white people" and aligned with eugenics. In fact, it's the study of human genetic variation [0], which has many implications for fields such as healthcare.
As you can imagine, it's an extremely sensitive subject which is widely mischaracterized by people on both the left and the right for their own political ends.
Hmm, which geneticist coined the term? Oh, it was VDARE contributor Steve Sailer? The one who writes about black genetic inferiority and Jewish control of the media?
Ah, you're right, Marks clarifies that racists appropriated the term he coined (http://anthropomics2.blogspot.com/2019/12/i-coined-phrase-hu...). Siskind obviously was referring to the nazi/alt-right/nrx meaning of the term, associated with Sailer, though.
Well, Jews are 3x over-represented in US Congress and to a variable degree in other high-effort, high-reward areas such as law and yes, media management.
Unless you'd suspect a conspiracy, there has to be a genetic or a cultural reason for that and the problem with that is that any such reason could plausibly apply to Black Americans.
To all the people who consider these ideas criminal, a little thought experiment:
A tribe has been discovered that is a close approximation of Homo heidelbergensis. They have basic language (100 words or so) and craft brutish tools, but, whatever you do, do not advance further than a 10 year old Homo sapiens in most areas of their mental development, however are way more aggressive and physically strong. Babies adopted into H. sapiens show improvement, but still markedly fall behind, never able to learn to read.
What should the public policy with regards to these people be? Should they be considered sui juris and generally held to the standards of the rest of the world? Should they be isolated and forbidden for contact?
Alternatively, a gene has been discovered in 0.01% of humans that, if present in 2 copies, produces an Einstein of sorts, less childhood problems. Should the carriers of the gene be allowed to seek each other out? What should be the policy towards the lucky 25% of their children?
My take: this is a tricky ethical dilemma that we should thoroughly explore in fiction. I'm glad its premise is incredibly unlikely, but the future is scary and might need a solution to the problem.
It's an admission that I don't know the answers. Honestly, I'm suspicious of somebody who claims to have the answers, here; they'd have to have a pretty darn good argument behind it, because people have been trying to solve this since before WWII.
The automatic characterization of examining human biodiversity as "Nazi race science" is a little concerning to me. While I understand that 95% of the people intrigued by HBD probably aren't in it for the sake of biology as much as they are for the sake of bigotry, I feel that Scott's treatment of it in that email was fairly reasonable. I certainly don't know enough about genetics, nature vs nurture, impacts of socioeconomics and culture, etc. to have an opinion on HBD, but I'm tentatively willing to acknowledge that there are probably at least two people groups in the world whose brains have adapted differently to different problem domains (though I'm strongly opposed to the idea that those two groups are "black people in the USA" and "white people in the USA"). If this wasn't true, it would be surprising enough to me that I'd need reasonable evidence to the contrary. If it is true, then it's likely significant, and needs to be talked about with the appropriate level of discourse. From his other writing, I feel like Scott understands this, and him limiting his statement on HBD to an email is due to the fact that it's incredibly hard to do so responsibly, and incredibly scary - e.g. my green account and the fact I fired up Tor to write this.
