
==== Front
Proc Natl Acad Sci U S A
Proc Natl Acad Sci U S A
PNAS
Proceedings of the National Academy of Sciences of the United States of America
0027-8424
1091-6490
National Academy of Sciences

39172774
202414870
10.1073/pnas.2414870121
retroRetrospective97
Retrospective
David Penny—An indomitable evolutionary biologist
Charleston Michael A. Michael.Charleston@utas.edu.au
a 1 https://orcid.org/0000-0001-8385-341X

aSchool of Natural Sciences, University of Tasmania, Hobart, TAS 7001, Australia
1Email: Michael.Charleston@utas.edu.au.
22 8 2024
3 9 2024
22 8 2024
121 36 e2414870121Copyright © 2024 the Author(s). Published by PNAS.
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ This article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).

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pmc(Edward) David Penny (DP) was born on September 28,1938, in Taumarunui, Central North Island, New Zealand. He passed away on May 20, 2024, in the company of his daughter Kim, in Palmerston North, North Island. He attended New Plymouth Boy’s High School, the University of Canterbury, and completed his PhD at Yale University, graduating in 1965. In 1966, he returned to New Zealand (after a postdoc at McMaster University) and then took up a position at Massey University in Palmerston North, New Zealand, where he worked until his retirement in 2017. In 2018, David was awarded the honor of becoming an International Member of the National Academy of Sciences, US.

I first met David Penny when I was contemplating what to do for a PhD; this would have been in 1990, I think. Would it be mathematical biology, in this “phylogenetics” thing, or would it be in theoretical particle physics? I’d spoken to David’s long-time collaborator, mathematician Michael (Mike) Hendy, who’d been my lecturer for my undergraduate and honors, and who’d suggested phylogenetics might be an interesting topic for me; and I was sort of interested, though hadn’t really considered, up to that point, moving into something as unclean and messy as biology.

I went to see DP in his office: computers and papers everywhere, in some kind of organized chaos that I have inadvertently attempted to reproduce in my own workplace. He talked about evolutionary trees, big picture stuff, patterns of the origins and diversification of life, programming (he was a long-time fan of FORTRAN, poor man), Mike’s new Hadamard conjugation method that was so elegant, and I’m sure there was something about how a PhD would work, but I have the sense that that kind of administrative detail was uninteresting and could largely just be ignored—at least until an administrator came knocking. He didn’t care about that then, and I wonder how much he ever did: Administration and bureaucracy were just things one had to manage (or avoid if possible) on the way to answering interesting questions. Mathematical biology was starting to look pretty good, and after a bit of vacillating, I went with these two wonderful people for my PhD (Fig. 1).

Left to Right: David Penny, Elizabeth Watson, Mike Hendy. Mike Hendy writes: Liz’s graduation photo was taken by Beth, who along with Sue Watson (Liz’s Mum), and Leo Watson (Liz’s son, then just a week old), were the entire audience attending this private graduation ceremony at Sue’s home in Hokowhitu. Image credit: Elizabeth Hendy (photographer).

At the time I had been told that these two were international experts, globally renowned, etc., but I didn’t realize this wasn’t just marketing—they had both recently been promoted to professor, sure, but it was when I told people at international conferences that I was/had been his student that I came to understand his (their) high regard internationally. He and Mike created, and led, the Alan Wilson Centre from 2002 to 2010, which became an internationally recognized center of absolute excellence. It really was the place to be, to study the big questions of life, the universe, and everything, through analysis of molecular sequences.

David was a wonderfully kind man. He looked after all of us; always made time for us, and even helped our taxonomic cousins through his involvement with the Great Ape Project—campaigning for basic rights of life to hominids, with progress in the form of the Animal Welfare Act 1999 (New Zealand). He made me realize that a good measure of a great PhD supervisor was not their international reputation (well deserved), or number of publications (huge), it was their kindness, their ability to inspire curiosity and create drive and independence, and to work to the highest possible standards, and how much one kept working with them even though we never worked in the same institution again. I often sought him out, years after I finished my PhD, to bounce crazy ideas off him—sometimes they’d turn out to be stupid of course, but David was never dismissive of them: He was always respectful, with maybe a twinkle in his eye.

He was always, always driven by curiosity; it was infectious, it was passionate, it was occasionally controversial, and it was compelling. You couldn’t help but be drawn in. One of the phrases I started to dread as I was trying to write up my thesis was “Now that’s a very interesting question!”–at one point I had to say “No David, it’s not! It won’t be until after I submit!” But he was, of course, right: It was always an interesting question. He never appeared to run out of them!

Unsurprisingly there’s been a thread of remembrances circulating through David’s academic progeny, a great big family, now all over the world, who echo what an inspiration he was. He was well loved and I think we all appreciate how incredibly lucky we were to have this wonderful man give us so much.

So, here are a few of those snippets, and some more that come to mind: He used to say “Pseudo-samples give pseudo confidence” (a commentary on bootstrapping), “computers are cheap: People are expensive,” and “To prove your supervisor wrong once is a tragedy, but to do it twice is carelessness.”

He made fun of The One Tree (Stephen Donaldson reference) to Rule Them All (Tolkien) as not being The Answer—he was much more interested in what more the tree would tell us. His regular attendance at the New Zealand Phylogenetics Meetings (Fig. 2)—referred to as Doom X in those years (X) is held at Tongariro National Park in the Central North Island after it was noted that Ngauruhoe played Mount Doom in the Lord of the Rings movies. At those meetings, David would sometimes appear to doze off in the front row of a talk (there would be snoring), but then somehow ask the most on-point question at the end—I still don’t know how he did that. The “Penny Ante”—a research question, posed by David at the same Meetings, whose correct answer would win a bottle of single malt whisky (or equivalent if that wasn’t your thing) bought by David. His ingenious practice at the Allan Wilson Centre of going around the lab the day before weekly meetings and “randomly” picking a speaker: thus, ensuring no one spent too much time on it, but keeping people on their toes (yes, people apparently hid). How fast he drove: He used to maintain his car knew the road between Wellington and Palmerston North better than he did. His appreciation of having a tame mathematician (and he had many).

David at the annual New Zealand Phylogenetics meeting conference dinner, in Waiheke Island, 2017.

Mike Hendy sent me this additional memory too, by email: “David kept abreast of the technology, seemed to be aware of developments before most of us. He was hailed by the MU (Massey University) Computer Centre as the first MU academic to send an email, when that facility was introduced. In the quest of computing speed, he purchased a RISC computer chip mid-1980s to enhance our B&B MP [Branch & Bound Maximum Parsimony] tree search.

He was one of the first, too, to get a PC—clunky, heavy with CRT screen—but this failed the "roll it down the stairs test" when he was leaving his Wellington home (he was late, as always, trying to carry PC and papers down in one load). A curious feature was when we began communicating using Skype, his image would appear upside down on our screens. That didn’t bother him, he would tell overseas correspondents that it was because he was in the Southern Hemisphere.”

I cannot do justice to the scientific contribution David has made to the world. He developed some of the first tests of evolution using DNA; he and his colleagues challenged the idea that Cretaceous-Tertiary (KT) heralded the radiation and diversification of birds and mammals. He created the branch-and-bound method to significantly speed up searches for most parsimonious trees. He was awarded the Marsden Medal in 2000 and the Rutherford Medal in 2004. He published over 300 papers and has been cited tens of thousands of times. In addition, he inspired us all to be better scientists, and better people, and to never stop asking those very interesting questions.

Rest in peace, David. Lots of love from us all.

Special thanks to Mike Hendy for error correction and additional content, to Beth Hendy for the photograph in Fig. 1, and to Barbara Holland and Trish McLenachan for guidance and feedback.

Author contributions

M.A.C. wrote the paper.

Competing interests

The author declares no competing interest.
